GB2615312A

GB2615312A - Birthing device

Info

Publication number: GB2615312A
Application number: GB2201260.3A
Authority: GB
Inventors: Guo Tianze
Original assignee: Birthglide Ltd
Current assignee: Birthglide Ltd
Priority date: 2022-02-01
Filing date: 2022-02-01
Publication date: 2023-08-09
Also published as: GB202201260D0; GB2615155A; GB202213813D0

Abstract

A device for assisting childbirth and/or preventing obstructed labour comprises a crown worn on a baby’s head, a bulbous rim defining an opening in the crown wherein the crown and rim are made from a hydrogel. The hydrogel may comprise water or a water-based lubricant. The hydrogel may be reinforced with synthetic polymer fibres such as nylon, polyamide, polyacrylonitrile, polyester, polypropylene, polybutester, polyurea, polyurethane. The device may be a sleeve with two openings defined by bulbous rims.

Description

BIRTHING DEVICE

Field of the Invention

The present invention relates to a device for assisting childbirth. The invention also relates to a method of making the device, a method of assisting childbirth using the device, and use of a hydrogel to assist childbirth.

Background

Labour can be divided into three stages: Stage I From the diagnosis of labour to full dilation of the cervix (10cm); Stage 2: From the full dilation of cervix to the delivery of the foetus. This usually last < 2 hours in nulliparous woman and 1 hour in multiparous woman; and Stage 3: From the delivery of the baby until complete delivery of placenta and membranes During second stage labour, the foetal head experiences significant friction from the mother's birth canal. The performance of a natural lubricant, which comprises a mixture of amniotic fluid, vernix caseosa and vaginal fluid, varies from person to person. The natural lubricant may not fully cover the sliding surface throughout the delivery process. Contact between the exposed skin and the birth canal in the absence of the natural lubricant can significantly increase the frictional force generated during labour and thus cause damage to the fragile mucus membrane of the birth canal. Damage to the mucus membrane induces local swelling, which further increase the frictional force generated during labour.

An artificial lubricant, such as a water-based lubricating gel, may be introduced into the birth canal during birth to alleviate this problem. However, the driving force provided by uterine contractions and maternal pushing comes in waves. Consequently, the motion of the foetus through the birth canal follows a start-stop pattern at low speed. Under such conditions, liquid lubricant may be pushed away from the sliding surface, exposing the sliding surface to boundary lubrication, which results in a significant increase in friction, in addition, water-based gel lubricants may reduce friction when initially applied. However, after a short duration, friction usually increases significantly due to the loss of water content because of factors such as evaporation and/or absorption. Increased friction can make the delivery of a baby even more difficult, particularly during obstructed labour.

Obstructed labour occurs (during stage 2) when despite strong uterine contractions, the presenting part of the foetus cannot progress through the birth canal. If not resolved quickly, it can lead to foetal and maternal complications. Obstructed labour can only be alleviated by means of an operative delivery, either by a caesarean section or by other instrumental delivery (forceps, vacuum extraction or symphysiotomy).

There is therefore a need for an improved means of assisting childbirth and/or preventing obstructed labour.

Statements of the Invention

According to a first aspect of the invention, there is provided a device for assisting childbirth, the device comprising: a crown for being worn on a baby's head; and a bulbous rim defining an opening in the crown wherein the opening is for receiving the baby's head, and wherein the crown and the rim are made from a hydrogel.

The device can be used to assist childbirth and prevent obstructed labour by (i) preventing direct (adhesive) contact between the skin of the unborn baby and the mucosa' tissue of the birth canal, and (ii) creating a (lubricious) hydrogel surface that contacts the mucosal tissue of the birth canal. Furthermore, the self-lubricating property of the hydrogel ensures that the device is consistently lubricated when it is in use. It also enables the device to be used for prolonged periods without becoming dry.

Preferably the hydrogel is reinforced with synthetic polymer fibres. The hydrogel of the crown may be reinforced with synthetic polymer fibres. The hydrogel of the bulbous rim may be reinforced with synthetic polymer fibres. The hydrogel of the crown may be reinforced with synthetic polymer fibres and the hydrogel of the bulbous rim may not be reinforced with synthetic polymer fibres. The hydrogel of the bulbous rim may be reinforced with synthetic polymer fibres and the hydrogel of the crown may not be reinforced with synthetic polymer fibres.

A device according to the invention may be a cap. In this embodiment, the opening in the crown is for receiving the circumference of a baby's head. The crown may be folded to create a double layer of hydrogel between the baby's head and the mucosal tissue of the birth canal.

A device according to the invention may be a sleeve. The sleeve may be used to assist childbirth by creating a lubricious surface that prevents direct contact between the skin of the baby (e.g., the head only, or part of or the entire body of the baby) and the mucosa' tissue of the birth canal. The sleeve may comprise a first opening and a second opening at the opposite end. The sleeve may have a first bulbous rim defining a first opening at one end and a second opening at the other end. The sleeve may comprise a second bulbous rim located between the first bulbous rim and the second opening. The first bulbous rim may be for sitting on top of a baby's head. Thus, the first bulbous rim may have a diameter (or largest length) smaller than that of a baby's head. The second bulbous rim may have a diameter (or largest length) greater than that of first bulbous rim. The second bulbous rim may have a diameter (or largest length) greater than that of a baby's head. The sleeve may be used as a crown. Thus, the crown may be for at least being worn on a baby's head. The sleeve may be folded to create a double layer of sleeve material between the baby's head (and optionally the baby's body) and the birth canal surface. The double layer of hydrogel enables easier passage of the baby through the birth canal.

The head of the baby is usually the most challenging body part to push out of the birth canal because of its size. Once the head has fully emerged from the birth canal, the rest of the body can be pushed out with relative ease. Thus, the cap may only cover the head of a baby. The cap may cover at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% of a baby's head while it is in the birth canal. The sleeve may, however, be used to cover at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% of a baby's body while it is in the birth canal.

The crown may be made from one or more separate panels of hydrogel. The crown of the cap may comprise a handle to aid removal of the cap. The cap may comprise a handle connected to the crown via an extraction cord in order to aid removal of the cap. Preferably the extraction cord is attached to the upper half and outer surface of the crown. The crown may be dome shaped.

The opening of the cap may have a diameter (or largest length) of more than 7 cm, or more than 8 cm, or more than 9 cm. The opening of the cap may have a diameter between about 7 cm and about 12cm, preferably between about 8 cm and about 14 cm.

The first opening of the sleeve may have a diameter (or largest length) of less than 12 cm, or less than II cm, or less than 10 cm, or less than 9 cm, or less than 8 cm. The second opening of the sleeve may have a diameter of more than 7 cm, or more than 8 cm, or more than 9 cm. The first opening of the sleeve may have a diameter (or largest length) of between about 7 cm and about 12 cm. Preferably the diameter (or largest length) of the first opening is smaller than that of the second opening. Thus, the diameter (or largest length) of the second opening may be about 12 cm or greater, about 14 cm or greater, or about 16 cm or greater. Preferably the diameter (or largest length) of the second opening is about 16 cm.

The (first and second) bulbous rim may be any closed loop shape such as square, oval or circular. Preferably, the bulbous rim(s) is/are oval or circular in shape. Preferably, the bulbous rim(s) form(s) an oval or circular shape along the circumference of the opening. The cross-section of the bulbous rim(s) may be any shape, including square, oval or circular. Preferably cross-section of the bulbous rim(s) is/are oval or circular. The thickness of the bulbous rim(s) may be less than about 10 mm, less than about 9 mm, less than about 8 mm, less than about 7 mm, less than about 6 mm, less than about 5 mm, less than about 4 mm, or less than about 3 mm. The thickness of the rim(s) may be greater than about 2 mm, greater than about 3 mm or greater than about 4 mm. The thickness of the rim(s) may be between about 2 mm and 10 mm. Preferably the thickness of the rim(s) is/are between about 2 mm and about 5 mm. The lubricious nature of the hydrogel makes the crown difficult to grip or handle. The bulbous rim(s) improve(s) the ease with which the cap can be handled.

The hydrogel may be made from a 3D network of a hydrophilic polymer emersed in a liquid. The liquid may be absorbed by the 3D network of hydrophilic polymer and thus cause the 3D network to swell. Thus, the term "hydrogel" can refer to a 3D network of crosslinked hydrophilic polymer that comprises a liquid, which causes the network to swell. A benefit of using a hydrogel as part of the invention is its self-lubricating property. When placed under pressure, hydrogels release the liquid (e.g., water) at the contact surface, thus maintaining fluid-film lubrication and drastically reducing the level of friction (the friction coefficient). In addition, hydrogels are highly absorbent.

The device may be unitary. The device may be a unitary hydrogel. The device may be moulded. Preferably the hydrogel does not dissolve in a liquid, such as water. The hydrogel may be a physically crosslinked hydrogel or a chemically crosslinked hydrogel.

The hydrophilic polymer of the hydrogel may be natural or synthetic. Natural hydrophilic polymers include hyaluronic acid, chitosan, alginate, collagen, silk and fibroin. Synthetic hydrophilic polymers include polyvinyl alcohol (PVA), polyacrylamide (PAAm), a polyhydroxyethylmethacrylate (HEMA) copolymer, polyethylene glycol (PEG), and polydimethylsiloxane (PDMS). Preferably the hydrophilic polymer of the hydrogel is synthetic.

Preferably the hydrogel is biocompatiblc. Thus, the hydrophilic polymer and the fluid may be biocompatible. Biocompatible hydrophilic polymers include PVA, PEG, PAAm, HEMA. PDMS, and mixtures thereof.

Thus, the hydrogel may be made from one or more of the polymers selected from the group consisting of: PVA, PEG, PAAm, a HEMA copolymer, and PDMS.

The hydrogel may be made from PAAm. Thus, the polymer of the hydrogel may be PAAm. PAAm creates hydrogels with an extremely low friction coefficient.

The hydrogel may be made from a 1-IEN1A copolymer such as poly(2-hydroxyethyl methacrylate/methacrylic acid (HEMA-MAA) or HEMA-Vinyl Pyrrolidone (HEMAVP). Thus, the polymer of the hydrogel may be HEMA-MAA or HEMA-VP. HEMA copolymers create hydrogels that are strong and stretchy, and thus more capable of withstanding tearing forces that are encountered during labour.

The hydrogel may be made from PVA. Thus, the polymer of the hydrogel may be PVA. PVA creates hydrogcls that are stretchy, and thus more capable of withstanding tearing forces cncoimtered during labour.

Preferably the hydrophilic polymer is PAAm, PVA, or a HEMA copolymer. Thus, the hydrogel may be made from PAAm. PVA, or a HEMA copolymer. More preferably the hydrophilic polymer is a HEMA copolymer, or PVA. Thus, the hydrogel may be made from PVA, or a HEMA copolymer. Most preferably the hydrophilic polymer is PVA. Thus, the hydrogel may be made from PVA.

The polymer of the hydrogel may be about 5% PVA to about 20% PVA (w/w). Hydrogels made from polymers comprising about 5% PVA have a low coefficient of friction. Preferably the polymer of the hydrogel is about 15% PVA (w/w). Hydrogels made from a polymer comprising about 15% PVA have a low friction coefficient and exhibit some elasticity. The polymer of the hydrogel (e.g., HEMA copolymer, PVA or PAAm) may comprise or be mixed with water. Thus, for example, the polymer of the hydrogel may be about 95% water to about 80% water (w/w) and about 5% PVA to about 20% PVA (w/w).

The polymer of the hydrogel may be about 7.5% to PAAm to about 20% PAAm (w/w). Hydrogels made from polymers comprising about 7.5% PAAm have a low friction coefficient. Preferably the polymer of the hydrogel is about 15% PAAm (w/w). Hydrogels made from a polymer comprising about 15% PAAm have a low friction coefficient and are strong when combined with a mesh. Thus, for example, the polymer of the hydrogel may be about 92.5% water to about 80% water (w/w) and about 7.5% PAAm to about 20% PAAm (w/w).

The polymer of the hydrogel may be a HEMA copolymer. The polymer may be about 40% to about 98% HEMA copolymer (w/w). In embodiments where the HEMA-copolymer is HEMA-MAA, the polymer may comprise about 90% to about 98% HEMA-MAA (w/w). Thus, for example, the polymer may be about 90% to about 98% HEMA-MAA (w/w) and about 10% to about 2% water (w/w). In embodiments where the HEMA-copolymer is HEMA-VP, the polymer may comprise about 90% to about 40% HEMA-VP (w/w). Thus, for example, the polymer may be about 90% to about 40% HEMA-VP (w/w) and about 10% to about 60% water (w/w).

Once the polymer of the hydrogel has been created (e.g., by mixing the polymer (powder) with water, and then drying the mixture), a liquid may be added to the polymer (e.g., the dried mixture) to create a hydrogel. The liquid may be water (e.g., deionised water) or a water-based lubricant. A water-based lubricant may be an aqueous solution. A water-based lubricant may not comprise an oil or a silicone-containing lubricant. The liquid (e.g., water) of the hydrogel acts as a lubricant and thus makes the hydrogel lubricious. The highly absorbent nature of the hydrogel may cause the device to absorb natural lubricants from within a birth canal.

The presence of the liquid (e.g., water) in the hydrogel causes the hydrophilic polymer of the hydrogel to swell. The swell ratio of the polymer may be between 2-20:1.

In one embodiment, the hydrogel comprises a 3D network of a hydrophilic polymer (e.g., PVA, or a HEMA copolymer) and water (e.g., deionised water) to encourage swelling of the 3D network. Thus, the hydrogel may comprise a 3D network of PVA and water (e.g., deionised water) The skilled person will appreciate that the thicker the hydrogel layer is, the more difficult it will be to place the cap on the head of a baby in a birth canal as well as the more difficult it will be to deliver the baby. However, the thinner the hydrogel layer is, the more prone that it is to being torn. Consequently, the hydrogel may comprise synthetic polymer fibres (e.g., polyamide fibres, such as nylon). The synthetic polymer fibres may be embedded or emersed within the hydrogel.

The synthetic polymer fibres may or may not be woven. The synthetic polymer fibres (e.g., polyamidc fibres, such as nylon) may form a mesh. The synthetic polymer fibres may form at least one layer, or two or more layers of synthetic polymer fibres. The layer(s) of synthetic polymer fibres may or may not be porous. The layer of synthetic polymer may be a mesh, e.g., a knitted mesh. The mesh may be an open mesh, a filter mesh, a woven mesh, or a warp knit mesh. Preferably the mesh is warp knitted as this provides a smooth surface while maintaining reasonable flexibility at a thin thickness. The synthetic polymer fibres do not dissolve in the hydrogel or a liquid, such as water.

Advantageously, the synthetic polymer fibres enable the hydrogel of the device to have minimal thickness while maintaining low friction and good flexibility/tensile strength. The synthetic polymer fibres also prevent the network of hydrophilic polymer from deforming due to excess swelling. Thus, the synthetic polymer fibres enable the hydrogel to retain a well-defined structure.

The pores of the mesh or layer of synthetic polymer fibre may have a diameter (or largest length) of about 0.5 mm to about 20 mm. Pores within this range are capable of reinforcing the hydrogel and preventing it from excessive swelling. Preferably, the pores have a diameter (or largest length) of about 1.0 mm. The fibres of the mesh be between about 0.05 mm and 0.4 mm in thickness/diameter. Preferably the fibres of the mesh are about 0.2 mm in diameter/thickness. Most preferably, the mesh (e.g., polyamide) has a 0.4 mm by 0.4 mm pore size and fibres of about 0.2 mm thickness The synthetic polymer of the synthetic polymer fibres may be hydrophilic or hygroscopic. Thus, the synthetic polymer fibres may form hydrogen bonds with water molecules in the hydrogel. The water molecules may also form hydrogen bonds with the hydrophilic polymer of the hydrogel. Thus, hydrogen bonds help to prevent &lamination or separation of the hydrogel from the synthetic polymer fibres when the device is placed under stress. The synthetic polymer of the synthetic polymer fibres may be a selection of one or more from the group consisting of: polyamide nylon), a polyacrylonitrile, a polyester, a polypropylene, a polybutester, a polyurea, and a polyurethane. Preferably the synthetic polymer is a polyamide. More preferably the synthetic polymer is nylon or elastane (i.e., a copolymer of polyether and polyurea). More preferably the synthetic polymer fibres form at least one layer of a polyamide (e.g., nylon). The at least one layer of the porous polyamide may be porous.

In one embodiment, the synthetic polymer fibres are made from or comprise a polyamide (e.g., nylon), and the hydrogel is made from PVA and water (e.g., deionised water), in another embodiment, the synthetic polymer fibres are made from or comprise a polyamide (e.g., nylon), and the hydrogel is made from or comprises a HEMA copolymer and water (e.g., deionised water). In another embodiment, the synthetic polymer fibres are made from or comprise a polyamide (e.g., nylon), and the hydrogel is made from or comprises a PAAm copolymer and water (e.g.. deionised water). The synthetic polymer fibres may be made into a mesh by warp knitting The hydrogel crown may be less than 2 mm, less than 1.5 mm, less than 1.0 mm, or less than 0.5 mm in thickness. The hydrogel crown may be greater than 0.01 mm, greater than 0.05 mm, greater than 0.1 mm, greater than 0.2 mm, greater than 0.25 mm, or greater than 0.3 mm in thickness. Preferably hydrogel crown is between about 0.1 mm and 2 mm in thickness, or between about 0.05 mm and 0.5 mm in thickness. The crown may be of uniform thickness.

The bulbous rim is greater in thickness than the crown of the device. The bulbous rim may be at least about 5-fold, at least about 10-fold, at least about 20-fold thicker, at least about 50-fold thicker, or at least about 100-fold thicker than the crown. Preferably the bulbous rim is about 5-fold to about 10-fold thicker than the crown.

Most preferably the rim is about 5-fold thicker than the crown The crown may be between 0.5 mm and 2 mm in thickness and made from PVA hydrogel. The crown may be between 0.5 mm and 2 mm in thickness and made from 5% to 20% PVA hydrogel, The crown may be between 0.5 mm and 2 mm in thickness 20 and made from about 15% PVA hydrogel.

According to a second aspect of the invention, there is provided a method of making a device for assisting childbirth, the method comprising: moulding a hydrogel solution comprising synthetic polymer fibres into a device for assisting childbirth Moulding may comprise casting the hydrogel solution to create a cast comprising the hydrogel solution and synthetic polymer fibres; initiating hydrogel formation; and then curing the cast to form a device for assisting childbirth. Moulding may be injection moulding, case moulding, or compression moulding.

The hydrogel solution may be created by mixing a powder of hydrophilic polymer in a liquid to create a mixture. The liquid may be water, preferably deionised water.

The initiating step may comprise performing a heat-cooling method. In a heat-cooling method, the cast/mixture may be heated until a clear, transparent, viscous solution is created. The cast/mixture may be mixed during the heating step.

The curing step may comprise waiting for the cast to cure (or cool) at room temperature. The curing step may be performed at about 10 to about 25 T. Preferably the curing step is performed at about 20'C. The curing step may comprise using UV light.

The curing step may be at least about 10 minutes, at least about 20 minutes or at least about 30 minutes long. Preferably the curing step is at least about 30 minutes long. The cooling step may be at least about 10 minutes to about 50 minutes, or about 20 minutes to about 40 minutes Thus, the curing step may be performed at about 10'C to about 25'C for about 20 minutes to about 40 minutes.

The method may further comprise performing one, two, three or four freeze-thaw cycle(s), preferably after the curing step. Preferably the method further comprises performing two or three freeze-thaw cycles after the curing step. The freeze-thaw cycles influence the mechanical properties of the hydrogel A freeze-thaw cycle may comprise freezing the device at about -35T to about -1ST for at least about 12 hours, followed by thawing the device at about 4'C for at least about 4 hours. Preferably a freeze-thaw cycle comprises freezing the device at about - 25°C for at least about 12 hours, followed by thawing the device at about 4'C for about 4 hours The method may further comprise hydrating the device, preferably after a freeze-thawing step. Hydrating the device may be performed by placing it in a liquid, such as water (e.g., deionised water) or an aqueous solution. The hydrating step may be performed (e.g., with water) for about 12 to 48 hours, for about 18 to 48 hours, or about 24 hours. Preferably the hydrating step is performed in water or aqueous solution for a maximum of about 48 hours. Preferably the hydrating step is performed at about 10°C to about 25'C for about 24 hours.

The method according to the second aspect may be used to create a device (e.g., a cap or a sleeve) according to the invention.

According to a third aspect, there is provided a device made or capable of being made by a method according to the invention.

According to a fourth aspect, there is provided a method of assisting childbirth by a pregnant subject, particularly by preventing obstructed labour, the method comprising: placing a device according to the first aspect of the invention on the head of a baby within the birth canal of the subject so as to assist childbirth.

Placing the device on the head of a baby while in the birth can& breaks contact between the baby's head and the mucosal tissue of the birth canal. Mechanical pressure placed on the hydrogel during labour causes the hydrogel to release its liquid (e.g., water) and thus generate a lubricating fluid film. The film is produced without requiring motion between baby and mother. This type of lubrication, which depends on the low compliance of the hydrogel and its ability to contain an interfacial water film even in the absence of relative motion, results in a stable and low friction interaction between the device and the tissue of the birth canal. Thus, the method of the invention enables one to assist childbirth or prevent obstructed labour by reducing the level of friction between the baby and the birth canal.

Placing the device on the head of a baby within the birth canal may comprise folding the crown or the sleeve such that there is a double layer of reinforced hydrogel between the baby's head and the birth canal The term "childbirth" herein refers to birth through the birth canal or unassisted vaginal delivery. Childbirth does not comprise childbirth through caesarean section.

Thus, childbirth for example includes a giving birth to a child in the breech position or exhibiting cephalic presentation (head-first). Preferably a sleeve according to the invention is used to deliver a baby in the breech position.

For childbirth to occur through the birth canal, the baby must pass through pelvis of the pregnant subject (see Figure 9).

The pelvic bone can bc dividcd into three regions, (1) the inlet (superior aperture), (2) the mid-cavity, and (3) the outlet (inferior aperture). The inlet is wider in the transverse direction than anteroposterior direction, the mid-cavity is circular, whereas the outlet is wider in the anteroposterior direction.

Preferably the method comprises placing the device on the head of the baby while the pregnant subject is in the second stage of labour. Thus, the method according to the third aspect comprises inserting the device into the birth canal of the subject and placing it on the head (and optionally the body) of the baby. However, the method according to the invention may include distributing a liquid lubricant over the outer surface of the cap prior to insertion into the birth canal or while it is in the birth canal.

Most preferably the method according to the invention comprises placing the device, IS (e.g., the sleeve or the cap) on the head of a baby exhibiting cephalic presentation (head-ti rst).

The foetal head is the widest part to gct through the passage during labour process, once the head is out of the passage, the rest of the labour is relatively easy to deliver.

The device of the invention may therefore be placed on the baby's head (and optionally the baby's body) to assist passage of the baby through the pelvis. Thus, the device may be placed on the baby once the widest part of the baby's head is in the inlet, the mid cavity, or the outlet. The device may be placed on the baby once the widest part of the baby's head has passed through the inlet or the mid cavity.

Station levels are used to assess the descent of the foetus through the birth canal, where station 0 is represented by the horizontal plane formed by the ischial spine in the mother's pelvic mid-cavity. Preferably the device is placed on the head of the baby once descent to station level 0 or more has occurred. Thus, the device may be placed on head of the baby once it has descended to station level 0 or more, 1 or more, 2 or more or 3 or more. Most preferably device is placed on head of the baby once it has descended to station level 1 or more.

The method according to the invention may be performed during an uncomplicated labour. For example, the method may comprise placing the device on head (and optionally the body) of a baby to assist the birth of a singleton. Thus, the method of the invention may not comprise placing the device on the head of a baby who is one of multiple babies from a single pregnancy. For example, the device may not be placed on the head of a twin, a triplet, a quadruplet, quintuplet, a sextuplet etc. The method according to the invention may comprise placing the device on the head of a baby during cephalic presentation.

The head of the baby comprises plates connected by sutures. The sutures between the bone plates are soft, during labour. Thus, the skull shape may change under pressure (moulding) to fit through the passage. Bone plates, may for example, overlap with each other during moulding.

In addition to the shape of the baby's head potentially changing during labour, the foetal attitude may vary. The attitude refers to the posture of the baby (i.e., flexed, deflexed, or extended). The attitude of the baby will thus determine how large the widest diameter will be, which in turn, effects the ease with which the baby is delivered.

The baby's head is not always completely flexed when it enters the pelvis. As the head descends into the narrower mid-pelvis, flexion occurs. The foetal chin tucks in towards its chest so the presenting diameter is smaller to allow easier passage through the mother's pelvic bone.

The widest diameter of the baby's head may be suboccipitobregmatic (well flexed), occipitofrontal (partially extended or deflexed), occipitomental (extended brow presentation) or submentobregmatic (hyperextended face presentation).

The device may be placed on the head of a baby while it is well flexed. The device may be placed on the head of a baby while it is partially extended or deflexed. The device may be placed on the head of a baby while it is in extended brow presentation. The device may be placed on the head of a baby while it is in hyperextended face presentation.

Preferably the device is placed on the head of a baby while it is suboccipitobregmatic (well flexed) or submentobregmatic (hyperextended face presentation).

The head of the baby may enter the pelvic inlet and exit the outlet in a different position. The baby may present in the outlet in an occipito-anterior (OA) position, such as a right occipito-anterior position, a straight occipito-anterior position, or a left occipito-anterior position. The baby may present in the outlet in an occipito-transverse (OT) position, such as a right occipito-transverse position, a straight occipitotransverse position, or a left occipito-transverse position. The baby may present in the outlet in an occipito-posterior (OP) position, such as a right occipito-posterior position, a straight occipito-posterior position, or a left occipito-posterior position. Preferably the baby presents in an OA position.

Thus, the device may be placed on a baby's head in an OA position, an OT position or an OP position.

The method according to the invention may comprise removing the device from the baby as soon as childbirth has occurred (i.e., once the baby has been delivered).

According to a fifth aspect, there is provided a use of a device according to the invention to assist childbirth and/or prevent obstructed labour during childbirth.

In another aspect of the invention, there is provided a device according to the invention for use in preventing obstructed labour during childbirth.

According to a sixth aspect, there is provided a use of a hydrogel to assist childbirth and/or prevent obstructed labour during childbirth.

In another aspect of the invention, there is provided a hydrogel for use in preventing obstructed labour during childbirth.

A "device" referred to herein may be a cap or a sleeve according to the invention.

The term "comprising may refer to "consisting or "consisting essentially of".

All of the embodiments and features described herein (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined with any of the above aspects or embodiments in any combination, unless stated otherwise with reference to a specific combinations, for example, combinations where at least some of such features and/or steps are mutually exclusive.

For a better understanding of the invention, and to show embodiments of the invention may be put into effect, reference will now be made, by way of example, to the accompanying drawings, in which:-Figure 1 is (A) a CAD of a cap according to the invention; and (B) a picture of a cap on the head of a training dummy.

Figure 2 is a picture of the head of a training dummy emerging from the birth canal of a birthing dummy while wearing a cap according to the invention.

Figure 3 is (A) a picture of a PAAm hydrogel sheet reinforced with a nylon warp knit mesh, (B) a picture of a HEMA copolymer (HEMA-MAA) hydrogel dish without a mesh, and (C) a PVA hydrogel sheet reinforced with a nylon warp knit mesh.

Figure 4 (A) is a schematic overview of a test setup used to measure the friction coefficient of SynDavent synthetic vaginal tissue vs synthetic skin tissue with the addition of a friction reducing material; (B) shows the experimental results obtained on the 2D bench setup under different conditions,"Syndaver dry" refers to SynDaverk skin vs vaginal tissue under padded dry conditions, "Syndaver wet" refers to SynDaverg skin vs vaginal tissue with excess water, "SynDavert hibitane" refers to SynDavert skin vs vaginal tissue with the lubricant, Hibitanem. "15% PVA (water)" refers to a hydrogel interface made with 15% PVA and water, "20% PVA (water)" refers to a hydrogel interface made with 20% PVA and water, "15% PVA hibitane" refers to a hydrogel interface made with 15% PVA and water and coated in the lubricant Hibitanem; and (C) shows the experimental results obtained from the 2D bench setup using various PAAm hydrogels -"Skin only" refers to the sliding surface was SynDaverk skin vs PAAm hydrogel, "Vag only" refers to the sliding surface was SynDavert vaginal tissue vs PAAm hydrogel, "Skin-Vag" refers to the sliding surface was SynDavcrt Skin vs vaginal tissue with PAAm hydrogel sandwiched between.

Figure 5 shows the effect of loading force applied on the static friction coefficient of a wet hydrogel sample (15% PVA) tested using a 2D setup (SynDavert) vaginal/skin tissue).

Figure 6 shows (A) a 3W-birth-simulator setup with an artificial head covered with SynDaverll foetal skin, positioned in an artificial birth canal lined with SynDavert vaginal tissue, (B) a close-up of the '3D'-birth-simu1ator setup with prototype visible between head and canal.

Figure 7 shows (A) the cumulative energy dissipation results for a simulated maternal push, where the foetal head was pushed through the birth canal of a 3D-birth simulator at a fixed speed and over the same distance, under various experiment conditions repeated three times each, "Wet" refers to a birth canal with excess water and no prototype, "Dry" refers to a moist birth canal padded dry with paper towel with no prototype, "Wet Prototype" refers to a birth canal with excess water and prototype on the foetal head, "Dry Prototype" refers to a moist birth canal with the prototype on the foetal head and (B) a summary of the results of Figure 7(A).

Figure 8 shows the static friction coefficient for a PVA hydrogel and a HEMA-MAA hydrogel obtained on the 2D bench setup of Figure 4, Figure 9 is an illustration of a device according to the invention placed on a baby's head while inside a birth canal during second stage labour.

Figure 10 shows (A) a perspective view of a hydrogel comprising a reinforcing mesh, (B) a plan view of a hydrogel comprising a reinforcing mesh, and (C) a picture of a 30 warp mesh Figure 11 is a picture of a nylon mesh on a mould (before the mesh moulded in a liquid of hydrophilic polymer).

Figure 12 is a picture of a sleeve according to one embodiment of the invention.

Examples

Figure 1 is (A) a CAD of a cap (la) according to one embodiment of the invention. The cap (la) comprises an opening (not shown) defined by a bulbous rim (3). in Figure 1(B), the cap (lb) is made from a PVA hydrogel reinforced with a nylon mesh (2). The cap has been made by attaching (e.g., sewing) several sheets of reinforced hydrogel together. Thus, the cap also comprises a seam (5).

Referring to Figure 2, there is shown a birthing dummy (7) being used by a childbirth trainer. The head of a training dummy within the birth canal of the birthing dummy is covered by a cap (1) according to the invention. The cap is inserted into the birth canal and onto to the head of the baby before it emerges so as to assist delivery of the training dummy.

Referring to Figure 3(A), there is shown a picture of a PAAm hydrogel sheet that contains a nylon mesh. Figure 3(B) is a picture of a hydrogel made from a HEMA based copolymer (HEMA-MAA). Figure 3(C) is a picture of a PVA hydrogel that contains a nylon mesh. The glossy appearance of the hydrogel is caused by water stored within the pores of the hydrogel and the mcsh, In use, the hydrogel sheet is used to create a cap according to the invention. Alternatives and modifications within the scope of the invention will be apparent to the skilled person. For example, the hydrogel may be made from a polyacrylamide, polyvinyl alcohol (PVA), polvacrylamide (PAAm), HEMA-based copolymer, polyethylene glycol (PEG), polydimethylsiloxane (PDMS) or mixtures thereof; contain a water-based lubricant; and the synthetic polymer fibres may form a non-porous layer.

Referring to Figure 4(A), there is shown a 2D' bench setup for measuring sliding friction. Tribological testing to determine the friction coefficient of a hydrogel is carried out using a Biotribometer machine (PCS Instruments). The machine features a moving top component that slides against a fixed bottom plate with a specified load applied. The test involves fixing two materials to the top arm and the bottom plate in order to determine the friction coefficient of the relevant tribosystem comprising the two materials. For example, a skin mimic (SynDaverk) and a vagina mimicking material from SynDaverlkl. A vagina mimicking material from SynDaverk is applied to the bottom plate while a skin mimic is applied to the top arm to simulate the in vivo scenario more closely. Hydrogel samples are then placed between the two skin mimics and allowed to slide freely. An applied load of, for example, 1N over a stroke length of 20 mm at 0.5 mm/s speed is used to evaluate the effective friction coefficient of the system.

Figure 4(B) is a summary of experimental results obtained using the 2D' bench setup. The results clearly show that placing a hydrogel, such as PVA, between the "vaginal tissue" and "skin", significantly reduces static/sliding friction.

Figure 5 shows that the greater the force applied to the specimen tissue the smaller the frictional coefficient becomes in the presence of a hydrogel according to the invention.

Figure 6(A) and 6(B) shows a 3D'-birth-simulator setup with an artificial head positioned in a birth canal. The simulator is used to measure the amount of energy required to slide a baby's head through a birth canal, as well as enable a user to measure average steady state force Figures 7(A) and 7(B) show that introduction of various prototypes into the 3D'-birth-simulator setup reduces the energy required to slide the head through the birth canal by about 40%.

Figure 8 shows that static friction coefficient of a hydrogel made with the PVA and a separate hydrogel made with HEMA-MAA (poly(2-hydroxyethyl methacrylate/methacrylic acid). The static friction coefficients were obtained using the 2D' bench setup described above. The HEMA-based hydrogel has a coefficient of friction which is more than 6-fold smaller than that of PVA.

Figures 10 (A) and 10(B) show a nylon mesh (9) embedded in a hydrogel (10). Figure 10(C) shows a picture of a nylon warp knit mesh.

Example 1 -Manufacturing a 15% PVA hydrogel cap comprising a mesh The Materials Poly(vinyl alcohol) "PVA" (146,000-186,000 g mot', CAS: 9002-89-5) and deionised water were supplied by Sigma-Aldrich UK. A nylon (warp knitted) mesh. A beaker, made from borosilicate glass, was used as it can withstand the high temperature and pressure that it will be exposed to.

An example of the constituent amounts is listed in Table 1. The total weight can be adjusted depending on the sizes of the moulded product.

Table l -Calculated weights' for PVA. to he. scaled as desired.

PVA 15% Weight PVA powder 15 (g) DI water 85 (g) Protocol: Place the nylon (warp knitted) mesh in a mould.

Measure DI water and PVA powder constituents and place them into separate beakers.

Place the 15% PVA mixture into high temperature pressure cooker or equivalent and set to 'High' for 1 hr. Stop cooker every 20 mins and mix manually.

This means after 20 mins, stop the cooker, take out the beaker, mix the solution manually and thoroughly i.e., with a metal spatula or something equivalent (not plastic as it might melt) and put it back into the cooker, set it on 'High' for another 20 mins, take it out, mix it manually, and so on, for around Ihr total cooking time. After 1 hr cooking time, the final solution should be clear, transparent (all PVA particles should have dissolved) and highly viscous. If it is not, continue repeating the cooking and mixing cycle until the correct solution is achieved. If the solution is a jelly that is either because the solution has not been heated up enough to where all the PVA particles have dissolved, or the manual mixing was not sufficient.

Take care to avoid excessive evaporation during the process; if using a conical flask, the screw cap should be loosely fitted and if using an open flask, aluminium foil should be fitted to cover the flask opening While boiling and straight out of the pressure cooker, pour 15% PVA into mould and close the mould. I0 3

7, Wait 30 mins for it to cool and settle.

8. Place in a freezer (approx. -25 °C) for 18 h (overnight).

9. Thaw at 4°C (in a fridge) for 4 hrs. Bring sample to room temperature (1 hr). 10 Demould and hydrate the cap in deionised (DI) water for about 241irs Example 2 -Manufacturing a HEMA-MAA hvdrogel sleeve comprising a mesh The Materials 2-Hydroxyethyl methacrylate "TEMA", Methacrylic acid "MAA", Ethylene glycol 10 dimethacrylate "EGDMA", 2,2'-Azobis(2-methylpropionamidine) dihydrochloride "Azobis" by Sigma-Aldrich UK and deionized water "DI water". A nylon (warp knitted) mesh.

Equipment Weighing scale, weighing paper, spatula, a beaker made from borosilicate glass and plastic screw lid, magnetic stirring bar, magnetic stirrer, plastic petri dish, ultrasonic bath, nitrogen gas, chemical fume hood, UV curing machine (I2W LED UV at 365nm).

An example of the constituent amounts is listed in Table 2. The total amount can be adjusted depending on the sizes of the moulded product.

Table 2 -Calculated weights.for ingredient for 11 EA/1244114A gel, to be scaled as desired.

HEMA-MAA(95-5) Weight HEMA 9.5 (g) MAA 0.5 (g) EGDMA 0.23 (g) DI Water 1.14 (g) Azobis 0.11 (g) Protocol: 1. Place the nylon (warp knitted) mesh in a mould.

2 Measure DI water weight directly in glass beaker. Measure all constituents and pour into the water in the beaker. Be careful not to breathe in monomer powders/MAA.

3 Place magnetic stirrer in the beaker, place a lid on the beaker and turn the magnetic stirrer on so that it stirs at fast but stable speed at room temperature until the constituents are dissolved (transparent and clear solution), and then leave to stir for an additional 30 mins.

4 Remove oxygen from the solution by bubbling nitrogen for 30 m -is and ultrasonic bath for 30 mins.

5 Pour the dissolved hydrogel solution into the mould.

6 Put the mould under UV light until the solution is cured (length of time is dependent on thickness of sample).

7 Submerge the hydrogel with the mould in an excessive volume of DI water (in this example, more than 2L) for at least 48 hrs.

8 Demould the shaped hydrogel.

9 Wearing gloves, drain water containing unreacted monomers out and rinse the HEMA-MAA samples a few more times under water.

Example 3 -Manufacturing a PAAm hydrogel cap comprising a mesh lhe Materials Acrvlamide, N,N'-Methylenebis(acrylamide) 2,2'-Azobis(2-methylpropionamidine) dihydrochloride "Azobis" by Sigma-Aldrich UK and deionized water "Di water".

Equipment Weighing scale, weighing paper, spatula, a beaker made from borosilicate glass and plastic screw lid magnetic stirring bar, magnetic stirrer, plastic petri dish, ultrasonic bath, nitrogen gas, chemical fume hood, UV curing machine (I2W LED UV at 365nm). A nylon (warp knitted) mesh.

An example of the constituent amounts is listed in Table 3. The total amount can be adjusted depending on the sizes of the moulded product.

Table 3 -Calculated weights for ingredient for PAAIn gel, to be scaled as desired.

PAAm (12.5%) Weight Acrylamide 7.1921 (g) Azobis 0.1726 (g) Bis 0.1726 (g) DI water 50 (g) Protocol: 1. Place the nylon (warp knitted) mesh in a mould.

2. Measure DI water weight directly in glass beaker. Measure all constituents and pour into the water in the beaker. Be careful not to breathe in the monomer powders.

3. Place a magnetic stirrer in the beaker, place lid on the beaker and turn the magnetic stirrer on so that it stirs at a fast but stable speed and room temperature until the constituents are dissolved (transparent and clear solution), and then leave to stir for an additional 30 mins.

4. Remove oxygen from the solution by bubbling nitrogen for 30 mins and ultrasonic bath for 30 min. 5. Pour the dissolved hydrogel solution into mould. The solution has a low viscosity so should be able to be easily poured into more complex moulds.

6. Put the mould under UV light until the solution is cured (length of time is dependent on thickness of sample).

7. Submerge the hydrogel with the mould in an excessive volume of DI water (in this example, more than 2L) for at least 48 hrs.

8. Demould the shaped hydrogel.

9. Wearing gloves, drain water containing unreacted monomers out and rinse the PAAm samples a few more times under water.

Claims

Claims 1 A device for assisting childbirth, the device comprising: a crown for being worn on a baby's head; and a bulbous rim defining an opening in the crown; wherein the opening is for receiving the baby's head, and wherein the crown and the rim are made from a hydrogel. 2. 3. 4. 6. 7. 8. 9.
The device according to claim 1, wherein the hydrogel is reinforced with synthetic polymer fibres.
The device according to claim 1, wherein the hydrogel comprises water or a water-based lubricant.
The device according to any one of the preceding claims, wherein the device is a cap.
The device according to any one of the preceding claims, wherein the device is a sleeve comprising a first bulbous rim defining a first opening at one end, a second opening at the other end, and a second bulbous rim located between the first bulbous rim and the second opening.
The device according to claim 4, wherein the opening of the cap has a diameter (or largest length) of about 8 cm to about 14 cm.
The device according to claim 5, wherein the first opening of the sleeve has a diameter (or largest length) between about 7 cm and 12 cm.
The device according to any one of claims 5 to 7, wherein the second opening of the sleeve has a diameter (or largest length) of about 16 cm.
The device according to any one of the preceding claims, wherein the hydrogel is biocompatiblc.
10. The device according to any one of the preceding claims, wherein the hydrogel is made from one or more polymers selected from the group consisting of PVA, PEG, PAAm, a HEMA copolymer and PDMS.
11. The device according to any one of the preceding claims, wherein the hydrogel is made from PVA. PAAm, or a HEMA copolymer.
12. The device according to any one of claims 2 to 11, wherein the synthetic polymer fibres are woven.
13. The device according to any one of claims 2 to 12, wherein the synthetic polymer fibres form a mesh.
14. The device according to claim 13, wherein the mesh is an open mesh, a filter mesh, a woven mesh, or a warp knit mesh
15. The device according to claim 13 or claim 14, wherein the mesh is a warp knit in
16. The device according to any one of claims 2 to 15, wherein the synthetic polymer fibres are made from a selection of one or more polymers from the group consisting of polyamidc (e.g., nylon), a polyacrylonitrile, a polyester, a polypropylene, a polybutester, a polyurea, and a polyurethane.
17. The device according to any one of claims 2 to 16, wherein the synthetic polymer fibres are made from a polyamide.
18. The device according to claim 17, wherein the synthetic polymer fibres are made from nylon.
19. The device according to any one of the preceding claims, wherein the hydrogel of the crown is between about 0.1 mm and 2 mm in thickness or between about 0.05 mm and 0.5 mm in thickness.
20. The device according to any one of the preceding claims, wherein the bulbous rim is about 5-fold thicker than the crown.
21 A method of making a device for assisting childbirth, the method comprising: moulding a hydrogel solution comprising synthetic polymer fibres into a device for assisting childbirth.
22. The method according to claim 21, wherein moulding comprises casting the hydrogel solution to create a cast comprising the hydrogel solution and synthetic polymer fibres; initiating hydrogel formation; and then curing the cast to form a device for assisting childbirth.
23. A method of assisting childbirth by a pregnant subject, the method comprising: placing a device according to the first aspect of the invention on the head of a baby within the birth canal of the subject so as to assist childbirth.
24. The method according to claim 23, wherein placing the device on the head of a baby within the birth canal comprises folding the crown or the sleeve such that there is a double layer of reinforced hydrogel between the baby's head and the birth canal.
25. The method according to any one of claims 23 or claim 24, wherein the device is placed on the head of a baby while it is suboccipitobregmatic (well flexed) or submentobregmatic (hyperextended face presentation).