A pregnancy is considered full term at forty weeks, so your estimated due date is calculated 40 weeks from the date of conception. Sadly, this system of calculation can lead to a somewhat inaccurate due date. One of the most common reasons for this due date likelihood of being erroneous is that many women do not have regular menstrual cycles. The pregnancy due date is calculated using an average menstrual cycle of every twenty eight days and the ovulation date being mid-cycle. For most women, this will simply mean that the estimated due date can be as much as a month off. It is important not to rely too much on the first due date that your health professional gives you. Many pregnancies, however, do not last for precisely 40 weeks. It is quite normal that the actual pregnancy due date is longer than this by up to two weeks.

A rough pregnancy due date is enough for most women to plan when they are going to file for maternity leave. Even if the due date isn’t entirely accurate, however,  it can be used as a good indicator of when the women can decide to stop working.  As the pregnancy progresses, the pregnancy due date can be estimated much more accurately by either an ultrasound scan or  a blood test. Read more . . .