blueash |
09-29-2017 08:58 AM |
While the timing of a pregnancy is given as 280 days, that is from the beginning of last menses, not the day of actual insemination. As a typical cycle is 28 days and fertility is maximum at midcycle ovulation, it really is about 265 days from sex to baby. And what day is 265 days before Sep 16th? Dec 25th.
If the frequency of sex were equal all days of the year, the most common birthdays would cluster around the days in the fall which are 25 hours long from the end of DST.
Interestingly the least common birthdates, after Feb 29th, are Dec 25 and Jan 1. Why? because no one is getting inductions or elective C Sections on those days.
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