A normal, full-term pregnancy is divided into three trimesters. Each trimester lasts The fetus will develop all of its organs by the end of the third month, so this is a crucial time. Part 3 of 5: Second Trimester It's dated from the first day of your last period, even though you actually conceive two weeks or so after this date.
There is no fool proof way to calculate the expected date of birth or due date Using this formula, the expected date of birth is calculated by adding 9 months to LMP, most women giving birth between 39 weeks and 41 weeks after conception. An egg is released into the fallopian tubes once a month to await fertilization.