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There are several "due date calculators" out there, and they all pretty much seem to give the same due date ... except in France!

See a striking example: http://www.babycenter.com/pregnancy-due-date-calculator It calculates the due date to May 26.

Then go to the French version of the SAME site: http://www.babycenter.fr/t400215/calculer-votre-date-daccouchement It calculates June 2nd.

Same goes if you go to a French doctor vs a US doctor (or Israeli, where I am).

This is science, biology, right? Why would there be a difference?

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5 or 6 days is not a striking difference. That due date has an accuracy measured in weeks, not days –  Chrys May 23 '14 at 11:15

1 Answer 1

up vote 6 down vote accepted

The reason for these is around the way they estimate the date of conception. In general, the first missed period is a useful indicator, but at what point in the previous few weeks do you set the conception point? It isn't obvious.

So although pregnancy is about 40 weeks, the start point may be guesstimated anywhere in a 2 or 3 week window, and that is obviously what has been done here.

I don't know why it is done differently in France (or if it is possibly just down to the calculators you have tried) but the thing to remember is:

  • odds of baby turning up on the stated due date are not that good anyway

So don't worry about it - during pregnancy checks, the due date estimate can be revised based on the development of the fetus, and he/she will turn up when ready :-)

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Hmm, good point. Too early in the morning. –  Joe May 23 '14 at 13:52

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