History and Development
The human 280 day gestation time [9 months +7 days] was originally codified in tables so that every day of the year had an equivalent due date of delivery. In the 1960s a circular calculator appeared which had two discs with both a 365 day and 40 week scale. These very useful devices continue to be supplied for free to clinicians by sales representatives. An added benefit for companies is the opportunity to brand the calculators with their corporate identities and messages. This popular design has remained unaltered for about 40 years.
Over the last 20 years routine Ultra-Sound examinations during pregnancy have made it necessary to make an additional calculation. The Traditional two disc calculator has to be moved to and fro for each calculation during which time it is difficult to remember the different dates it has indicated. The innovation of a third scale for Ultra-Sound calculations has made comparisons of the Due Date by the Calendar & U-Sound systems easy. It can immediately show the magnitude of any difference between the two methods of calculating the Expected Date of Delivery .
The British Department of Trade and Industry has supported this project at home and abroad and, to date, the Obdisk3 has been on British Embassy web-sites in Germany, Holland, Italy, Argentina and Kenya.
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