How We Calculate Due Dates
The general assumption now is that a woman should have a baby by 40 weeks gestation. This is based on a decades old assumption that is not necessarily based in fact but rather tradition. The method of calculating due dates most commonly used is known as Naegele's Rule and you can read more about it here.
- If you read the description you will find that: There are some imperfections in it that make it more of a rough estimate than an exact calculator
- Recent studies have shown that the average gestation is closer to 41 weeks and one day for first time mothers rather than 40 weeks.
What is the big deal about being post dates?
Officially you are not actually overdue until you go past 42 weeks! Yes- read that again- you are not overdue until you go past 42 weeks. Yet currently you will have a hard time finding a care provider that will "let" (I hate that term) you go past 41 weeks. So now, instead of 40 weeks being considered an average, give or a take a few weeks, you pretty much are expected to deliver by 41 weeks or induction is on the horizon.
What is going on here? Truthfully there are some risks to going overdue, they are however statistically small for most women. In fact, one article I found stated that:
"Routine labor induction at 41 weeks likely increases labor complications and operative delivery without significantly improving neonatal outcomes."
(ObstetGynecol 2000; 96: 291-4)
There is some evidence however that going overdue does increase the chance of neonatal death. "At 44 weeks the death rate of these infants escalates to at least four times that of term infants, although it is still less than 1%" (Ob Gyn News, July 15-31, 1996).
So- once we get past 42 weeks there is a slightly increased chance of neonatal death. We also can be pretty sure that the interventions used to start labor earlier also have risks and can be dangerous to both mother and baby.
Induction, Convenience, and Liability in Postdates
Right now we are seeing outrageous induction rates. They very from hospital to hospital and region to region, but, they are dangerously high and in my opinion, inductions are damaging women and their babies across the country right now.
They are not however causing hospitals to lose money. In fact, the opposite is probably true. Induced babies are more likely to have problems and need a stay in the NICU, and their mothers are more likely to "need" a costly c-section and the added hospital stay.
The other benefit to the induction prior to 42 weeks is that it can be planned. Ask a midwife when women go into labor- the answer will probably be- usually at night. Women often go into labor when their parasympathetic nervous system is activated and they are relaxed, like they are at night when asleep.
Now take a trip to your local L&D unit at a nearby hospital. You fill find (often, though it varies a lot) that hospitals are very empty at night and very busy on weekday mornings. Inductions can happen when you want them to. They are predictable. They can be scheduled. They can fit into your vacation, work schedule, sleep schedule, etc. Don't just blame the OB though, they can fit into your husbands travel schedule, or your kids school schedule. You can't predict how they will turn out, but you can pick the day. And let's face it, the last few weeks of a pregnancy are miserable. Women are BEGGING for inductions, sometimes starting as soon as 38 weeks.
Will We Ever Get Back to Just Allowing Birth to Happen?
I love to talk to women about birth, especially of different ages. I find that even 15 years ago doctors didn't really start to worry until you went past 42 weeks. Talk to your mothers and Aunts and friends. These women routinely went past 40 weeks and it was just not worried about that much. This is almost unheard of now as induction is so common and a naturally starting labor is quickly disappearing in our hospitals.
I hope that the pendulum of induction will swing the other way as we realize how dangerous the routine induction is and how much it is damaging not just babies (do we really know what pitocin does to their rapidly developing brains?) but to the psyche of women everywhere (does the thought that your body doesn't work properly and will never go into labor upset you?).
The convenience for the care provider and scheduling guru at your local hospital, not to mention you, seem so tempting that I worry that we will be slow to get back to the idea that labor can and will and SHOULD occur on its own when the baby is ready.
What Should You do if You Are Overdue?
I will tell you how I pesonally deal with being overdue. First, I am trying to be patient with my body and my baby. If you believe that birth is normal and safe and that babies come when they are ready (note the they, not you) than it is worth the wait to give your baby the best start possible. I will try to keep myself healthy and happy and feed my body right so that the baby can get any last minute things it needs before it can be born. I will try to learn some mothering skills from this little wait (like patience!). I will be grateful that my babies come a little late rather than dangerously early. I will be grateful for their health and their own personalities that choose when they are ready. I will do some natural things that prepare my body for birth, like walking, without trying to "induce myself". (I have always found the term 'natural induction' to be somewhat silly).
I will be grateful for all the women I know who believe in birth and allow it to happen naturally and support me even when I am feeling a little crazy!
Information from ACOG regarding post dates.
NB Editorial Note: It is important to stay in close contact with your healthcare provider for your entire pregnancy, but especially as you near your due date. While many inductions are for convenience, there are medically sound reasons to induce. Find a healthcare provider that you trust, and then listen to her!