Due Date Calculation Info:

Even when we go to see our doctors when we find out we are pregnant, we don't seem to get the right due date! Why are we getting mis-information? Here are some reasons why, and some information that you should know.

One point of confusion many women encounter is the calculation of due dates. "If I conceived a few weeks ago, why does the pregnancy wheel say I am 5 weeks pregnant?" is a common type of question.

Did you know that although an average pregnancy is counted as being 40 weeks long, you are only pregnant for 38 of those? The first two weeks you are "pregnant" are actually the first two weeks of your cycle - from the time you start your period (Day 1 of your cycle) to the day you ovulate and conceive your baby (the average for women is Day 14).

Another point of confusion is the discrepancy between the time we think we actually conceived and the time the doctors seem to think we did! This is often because our doctors use a pregnancy wheel that assumes a 28-day cycle. The problem with using this little wheel though, is that many women do not have the "average" 28-day cycle!

Although the "average" cycle is 28 days long, this is not always the case, which means women are not always ovulating on the 14th day of their cycle like that little wheel assumes. The myth of "day 14" is very common, and has certainly lead to more than a few miscalculated due dates (not to mention unplanned pregnancies!). Women have menstrual cycles that can be short (e.g. 26 days between two periods) or long (e.g. 40 days between two periods). If the pregnancy wheel is used to calculate their due dates based on a 28-day cycle, the dates could be off.

For example, a woman with a 35-day cycle will be told she is 6 weeks pregnant because her last period started 6 weeks ago. However, she may be only 5 weeks pregnant since she ovulated about a week or more later than the "usual" 14th day.

Given this information, it's no wonder women like you and I are more trusting of online pregnancy calendars (that take into account our cycle length and luteal phase length), than we are of those pregnancy wheels at the doctor's office!

Calculate your due date (accurately!) with YMH's Due Date Calculator: