The day you have sex does not mean that it is necessarily the day the sperm made contact with the egg. It can live In your bodies for days. Since drs still dont know exactly how long pregnancy should last and the science behind it is purely an average/estimate process there is going to be some inconsistencies. A dr usually wont change a due date over a week difference in growth or even two weeks but they have to go by baby since sperm doea live in you for several days up to a whole week even.
Not to mention they go off your LMP too.
i agree with ^^, in that case, we might have the same due date.. :) im due December 1--im 20 weeks and 4 days
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