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Understanding Your Pregnancy Due Date



Pregnancy Joy

The news and joy of finding out that you are pregnant will inevitably bring with it many feelings of uncertainty and confusion most especially if you are a first time Mum. You will have discovered through hear say about people carrying their baby for 9 months or for 40 weeks and so you presume that this will also be the case for you. However what comes as a surprise for many women is the fact research has shown (as per that only 5% of babies actually stay in utero (in the womb) for the full 40 weeks.


What is a due date?

What women should realize is that a full-term pregnancy can be anywhere from 38 weeks to 42 weeks long. We often hear about a baby born at 38 weeks is an ‘early’ arrival or similarly how one born at 42 weeks is a ‘late’ baby. This is actually incorrect in factual terms.


When is the real due date?

The main point that new Mums-to-be need to know is that the 40 weeks of pregnancy are not counted from the day of conception, in fact they are counted from the first day of your last menstrual period.



While this might seem a bit confusing as it is almost as though the pregnancy time clock begins before the sperm even meets the egg but it does make for a more accurate prediction of due date. This is because you can say for absolute certainty which day you began to bleed for your menstrual cycle but you (or a doctor) cannot do the same with as much accuracy for the day you ovulated.


To summarize

When it comes to predicting the date; the first day of your pregnancy begins on the first day of your last menstrual period (LMP). This is taking into account that your baby is technically about two weeks younger than that (most women ovulate and conceive two weeks after their LMP) and will only have covered 38 gestational weeks (the period of development in the uterus from conception until birth) by the time you reach 40 weeks. Many women have irregular menstrual cycles and so may have difficulty calculating their due dates (the LMP method is far from perfect), so talk to your doctor to get the best estimate of your pregnancy due date.


Submitted by Vanessa, a writer for