What Is Your Due Date?

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Remember when you were in school and your term paper had a due date?

Hand it in late and there were consequences. Not good ones either.  As a tax-paying citizen, you know that the due date for your taxes is April 15th. If you miss that date there is a penalty. Your rent or mortgage has a specific due date. It's important that you pay attention to that date, otherwise you could incur a fine or worse. In life we are faced with numerous due dates that we need to pay careful attention to. When you are pregnant you are also given a due date, however this is the one due date you don't need to pay such close attention to. 

Due dates are in fact estimated dates of delivery, and they can be off by as much as 2 to 4 weeks in either direction. That's a lot of wiggle room! Only about 5% of babies are born on their estimated due date. Unfortunately the plans, schedules and commitments of women, doctors and midwives are often based on a date that is at best arbitrary.

It's understandable that when you are in your ninth month and really ready to meet your baby, you want a date that you can focus on. You want something concrete to look forward to. But when that date comes and goes and still no baby, it may cause some anxiety about whether your baby is OK. When your due date passes, you may worry that your baby is getting too big and become concerned about the birth itself.  This is when it's good to remember that due dates are not accurate. Talk to your health care provider, listen to your intuition and stay calm.

Baby Weight and “Due Dates

Most doctors believe there is no reason to let the pregnancy go past the due date, and many doctors are reluctant to have a woman stay pregnant longer than 39 weeks. They typically believe that if the baby weighs 5 1/2 pounds, it is as healthy as it can be and there is no point to prolonging the pregnancy.  If your doctor is very liberal he or she may allow the pregnancy to progress to 42 weeks, but rarely longer than that. However, basing a “due date” solely on a calculation or baby’s estimated weight is not foolproof.

First of all, the way due dates are calculated is not very reliable (see below), so we don't really know how close the estimated due date is in reality. Secondly, the baby's weight can be off by 20%, so your baby may actually be smaller or larger than predicted.

Menstrual Cycles and Due Dates

Due dates are based on the length of a menstrual cycle - assumed to be 28 days. However, not every woman has a 28 day cycle. Some women have cycles that are 35 days, while others may have cycles of 45 days. Some women's cycles vary greatly month to month!

In addition, most women do not know the exact date of conception, so even if a woman does have a regular 28 day cycle, her conception date is merely an estimate. Typically conception occurs about 11-21 days after the first day of your last period, so when you conceived can affect the accuracy of your due date by as much as two weeks! And an Ultrasound is only 20% accurate, so even that is not a precise calculation.

When Will Your Baby Really Arrive?

The simple answer? When he or she is ready!

The truth of the matter is that your baby knows when he or she is ready to make an appearance, and labor ideally should begin when your baby is ready. The lungs are the last vital organ to develop, so once your baby's lungs are developed, they release a hormone which kick starts labor and the birth process. Your baby begins turning and moving in rhythm to your contractions.

I think it's interesting to note that the length of gestation runs in the maternal side of the family. So If your mother and your grandmother gave birth at 44 weeks there is a very strong chance that you will deliver at 44 weeks as well. Talk to your mom and your sisters. At what week did they give birth? This doesn't always hold true, but then neither does the due date your doctor gives you - and my guess is that talking to your family is probably more accurate!

Now I'd like to hear from you. Was your baby born before your due date, on your due date or past your due date? Please leave a comment below. It will be an interesting discussion.