This occurs when the egg is traveling down the fallopian tube.Eventually, the fertilized egg will find its way to the uterus and implant into the endometrium.If you don’t know this, a doctor can estimate the gestational age with an ultrasound or through a physical exam.All estimates, even by doctors, are “best guesses” and cannot tell you the actual day you conceived, due to varying growth rates of babies and differences in women’s individual menstrual cycles.
Ideally, this should be done between 9 and 13 weeks (based on your last menstrual period.)If the estimated ultrasound due date is less than 7 days different from the last menstrual cycle due date, your due date doesn’t change.Other studies say 282 days (or 40 weeks and 2 days) is better. On top of all this, there are a number of factors that may cause you to give birth sooner or later than average... But one gives birth earlier or later than the other. Age: Generally speaking, women who are 35 years or older tend to give birth earlier or later than their due dates.In fact, the older you are, the more likely you are to go over your official due date.In fact, according to one study, only 4% of women give birth exactly 280 days (or 40 weeks) from their last menstrual period.Just 70% will deliver within 10 days of their due date.