Lately, I've been reading a lot about the medical induction of labor. Reading about when and why parents should consider induction and about when it's best to wait and "let the baby decide."
Generally, what happens is that somewhere between 37 and 42 weeks, the baby will send out a hormone that tells your body that it's time to let the baby come out. Your cervix will start to soften and thin out in preparation for beginning to dilate. Uterine contractions will kick in and the the baby will move lower in the pelvis as the cervix opens up to allow the baby through the birth canal. In a normal, healthy mother (and a great number of unhealthy ones) this process will start when the baby and the woman's body are both ready for birth.
In 1830, a doctor named Franz Naegele invented the way that due dates are calculated. Doctors, who love numbers and being able to measure things, still use his formula today. The issue here is that the "due date" gives us a rough estimate of when a baby might decide to make his or her apearance. There are several factors that will affect how accurate a due date is, such as the length of that woman's menstrual cycle and how long the individual baby needs to mature.
Now, since doctors like measurements so very much, what tends to happen is that an OB will look at a "due date" as the actual date by which the baby needs to have arrived. If the baby continues inside the womb past the date that they've decided on, doctors will start to get nervous and begin talking to expectant parents about "inducing labor." Some doctors even want to talk induction before the "due date," because once a baby is considered full-term, they are more comfortable getting the baby out of the uterus (an environment that they can't control) and into the hospital where they can assess, measure, and test.
One thing that obstetricians in our area seem to do as a rule is to begin doing ultrasounds and non-stress tests once a mother hits 40 weeks. What they then do is tell parents that they have to come in to the office anywhere from every 2-4 days for more testing to make sure that everything's ok, creating the atmosphere for convincing parents that continuing a pregnancy at this length of gestation is risky and something that needs to be closely monitored. What seems to be the norm at these appointments is that the doctor will work on talking the parents into a medical induction.
Doctors will say things like:
"So, when do we want to schedule the induction?"
"If you go home now, I can't be held responsible for what happens."
"You'll be begging me to get that baby out of you be 39 weeks."
"I let you go this long." (OB to a mom who was 41 weeks)
"Because your cervix is lousy."
Quotes taken from My OB Said What?
To sum it up, the "due date" is a good predictor of what month you may end up having your baby, since it falls in the middle of the four week time span when most babies tend to make their appearance. Being 40 weeks, 41 weeks or 42 weeks along is not a medical reason for induction. It just means that your pregnancy isn't over and your baby is still maturing. If you choose an OB (and even some midwives do it) as your care provider and you go past 40 weeks, you need to be prepared to deal with pressure to induce labor.
In the coming posts, I'll be writing more about real reasons for induction, the Bishop score, natural ways of encouraging labor and handling when you are the one who is "post-dates."