Pregnancy Calendar By Day

Pregnancy Calendar By Day. You might also like my new pregnancy & childbirth book. Your due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (assuming a 28 day cycle).

From first day of your period to the first day of your next period. The cells inside the blastocyst (embryoblast) will develop into the fetus while the cells outside (trophoblast) will become the placenta.