GB2333869A - Pregnancy calculator - Google Patents

Abstract

A pregnancy calculator comprises three discs relatively rotatable about a central rivet. The outer disc A shows calender dates, the next disc B shows the expected date of delivery EDD based on the date of the last monthly period LMP, and the inner disc C shows the expected date of delivery EDD based on ultra-sound measurement. Any discrepancy in the calculated dates is readily apparent.

Description

Specification This device relates to a rotary calculator that will indicate any discrepancy between a pregnant woman's Expected Date of Delivery assessed by the calendar method and ultrasound measurements.

Historically calculations of a pregnant women's Expected Date of Delivery were made using an annual table of dates that added 280 days to each day of the year. For every pregnant women her Expected Date of Delivery ( E.D.D.) is usually estimated using the first day of her last menstrual period (Method I). This calculation is important for professional advisers who need to know accurately when a pregnancy is overdue for delivery. The woman also needs to know when she may deliver.

In the late 1950's a two-disc pocket rotary calculator was introduced to carry out this calculation and samples have continued to be in widespread use by Obstetricians, general practitioners and midwives throughout the World. Sometimes the date of the last menstrual period (L.M.P.) is not known and this can cause problems.

However since the 1980's it has also been possible to gain extra information of fetal maturity by measuring the size of a fetus 'in utero' with ultrasound scanning (Method II). From this information it is possible to calculate the Expected Date of Delivery with an accuracy of up-to 7 days.

Unfortunately there is no simple way of comparing calculations from the two Methods.

Currently the traditional device will not perform two simultaneous calculations at different times during the pregnancy and does not show any discrepancy.

This new device is simpler to use than a computer and will fit in the pocket of a white coat. It has three concentric discs which can rotate separately with a central rivet. The calculator will measure any discrepancy (in days) between a pregnant women's Expected Date of Delivery calculated by Calendar Method ( I ) and by the Ultrasound Method (it).

Disc A has around its periphery a calendar of 365 days and Disc B has around its periphery a scale of weeks. This is the Traditional calculator to which is added Disc C which is smaller and has around its periphery is a scale of weeks for the ultra-sound measurement. Discs B and C show the discrepancy in days between Methods I & II.

The basic markings on the three discs are as follows Figure 1 shows Discs A, B and C in their working positions.

Figure 2 shows Disc B only.

Figure 3 shows Disc C only.

By rotating the three discs to the correct dates using the traditional Method I and ultrasound Method II this calculator can simultaneously show and compare all the relevant dates during pregnancy and estimate the Expected Date of Delivery. It will show any discrepancy.

Claims (4)

1. Claim 1. The calculator will measure any discrepancy (in days) between a pregnant women's Expected Date of Delivery calculated by Calendar Method ( I ) and by the Ultrasound Method (it).
2. Claim 2. The device will show discrepancies between Method I & Method calculations throughout pregnancy.
3. Claim 3. The device will show the date of conception using Method I and/orMethod II.
4. Claim 4. The device can be used as an 'aide memoire' to show when any routine procedure should be carried out.