How to Work out Your Due Date

Once you find out that you are already pregnant and the emotions start to flood in, perhaps your next question is — when is my baby due?  Normal pregnancy often lasts 40 weeks (or about 280 days).  The first day of the last normal menstruation is used to make this calculation.

Calculating the due date is quite easy for those who already know the exact date of the first day of her very last menstruation.  You can do this by adding 9 months and 1 week to this date and voilà, you have a very good estimate of your due date for your pregnancy.  Alternately, you can use Naegel’s rule which involves subtracting 3 months from the first day of your last menstrual period (then adding one year, of course) and adding seven days.  Both methods result in the same estimate.  As well, calculators are also available to determine your due date.  Most doctors still use a pregnancy wheel–which you can now buy digital versions of for your iPhone.

However, there are limitations with using Naegel’s rule.  To start with, women who’ve recently used hormonal contraceptive methods (before becoming pregnant) or who don’t have regular cycles won’t get an exact result with this method.  What’s more is that Naegel’s rule is based on the assumption of women having regular 28-day cycles with ovulation occurring on day 14.

The majority of women, though, do not know their exact due dates.  This is because very few women take note of the first day of their menstrual cycle.  This is why about 80% of babies are born within ten days of the due date.  Just remember that a full term is 37-42 weeks of pregnancy.  Regardless of whether or not you do remember the first day of your last menstrual period (LMP), studies suggest that ultrasound estimation in the first half of pregnancy is superior to dating based on the first day of the LMP or physical exam.

Premature births (or preterm deliveries) often occur because the mother goes into labor earlier than expected.  Most of the time, there is no precise reason as to why early labor occurs but these are considered risk factors:

Post-term pregnancy has associated health risks–both to the mother as well as an increased incidence of perinatal mortality.  This is because, beyond the 42nd week of pregnancy, the placenta already ages and it soon loses its ability to transmit nutrients and the much-needed oxygen to the fetus.

Some cases could end up to fetal death.  If the fetus manages to live, it can have a wrinkled appearance, with long nails, and much hair.  Also, the fetus might already have eaten meconium or a fecal material that is passed into the amniotic fluid.  When this material enters the baby’s lungs prior to delivery, it might suffer from pneumonia after birth.

These are the reasons why computing the precise due date is necessary because the life of your child could depend on it.

Alan Murray is the webmaster for a baby girl names site. The site covers more that just baby names however, with section on baby health, pregnancy and pregnacy week by week.

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