I am not aware of any research to that effect. Nor does that even make sense. The median length of pregnancy, meaning half a population of healthy women who reached term would give birth before this date and the other half after it, is 41 wks 1 day in first-time mothers and 40 wks 3 days in women with prior births. So 40 wks puts you squarely in the middle of the normal range for length of pregnancy. Do you really think the process is designed that poorly? Even if what your ob says is true, which I very much doubt, it would say nothing about your ability to birth your baby. I'm afraid that what you are dealing with is an ob who doesn't really want to do a VBAC and is now looking for reasons to persuade you into repeat cesarean surgery. If this is the case, you may have a real problem on your hands because you will be depending on your ob's judgment, and if your doc prefers that you have surgery, it is easy to find a reason to do something you want to do. I think you might want to consult with someone at the International Cesarean Awareness Network (ICAN) to talk over your options for handling what could be a tricky situation for you.

Do not, by the way, agree to an induction as an alternative. Research shows that it decreases your chances for vaginal birth and a number of studies show it increases your risk of the scar giving way.

-- Henci

I don't know about research on molding, but it seems unlikely to me that this would be an issue.

Further, ultrasound measurements are NOTORIOUSLY inaccurate.  I had a client a year ago planning a VBAC who was told at her 40 week ultrasound that the baby was 10 lbs.  That day.  Not "predicted to be 10 lbs in a week."

She spent a week of MUCH stress arguing with her OB about laboring or not...

Baby was born at 41 weeks 1 day and weighed 8 lbs 12 oz.  No sign that he had lost weight due to placental insufficiency or anything like that.

Further, there is no way to really tell when you will spontaneously go into labor.  You can be tight as a drum one day, and holding your baby the next, or dialated to 3 cm/50% effaced for weeks.

Good luck!

Jenn

I have an 20 month old daughter born via cesarean at 35 weeks due to abruption. 

My doctor is now telling me, even though he agreed to a vbac, that my son's head circumference is 36cm at 39 weeks and that I am showing no signs of going into labour.  He is worried that after 40 weeks the head will lose some of its ability to mold and fit through the birth canal.  Is there any research to support the calcification of the bones after 40 weeks and that baby's head, past 40 weeks, do not mold as much?

Di