SMFM Video: What is the Optimal Time for Induction of Women Over 40?

Anjali Kaimal, MD, of Massachusetts General Hospital, discusses her research into optimal gestational age for induction in women over age 40 during the poster session at the Society of Maternal and Fetal Medicine's 32nd Annual Meeting. A transcript of the video is below.

My name is Anjali Kaimal and I’m maternal and fetal medicine doctor at Mass General Hospital, and this study was a decision analysis-so a mathematical model-to look at when the appropriate time is to deliver women who are having their first baby after the age of 40. So the idea behind the study is that women over 40 have an increased risk of C-section and also an increased risk of stillbirth. Induction is an intervention that we think can sometimes help to reduce some of those risks, but we want to be careful in terms of thinking about what the risk and benefits are.

Basically the way that the model works is that we start off with a cohort of women who are at 39 weeks, and then they can have a number of things happen to them: they can either go into labor; develop a reason to be induced; be induced electively; or go into spontaneous labor. So what the model shows is that if you think that this is an indication you might want to think about inducing someone for, probably the greatest benefit will be to induce them at 39 weeks.

So, 39, 40, or 41 weeks here all together. A 39 week induction is the most expensive, but also allows you to reduce the likelihood of IUFD the most. And 40 weeks falls right in the middle, but the greatest incremental cost-effectiveness is actually doing it at 39 weeks, because the amount of additional cost you have versus the amount of IUFDs that you’ve saved means that 39 weeks is the most optimal strategy.

So what I hope people will take away from this is that not necessarily that every woman over 40 needs to be induced,but instead that, when we think about when we want to induce, we think about balancing risks with benefits. We think that most of the stillbirths in this population are related to placental insufficiency; it may be that doing antenatal testing with things like non-stress testing and biophysical profiles would allow us to keep these women and babies safe. If we are concerned about the level of risk, probably the best way to reduce that is to induce people at 39 weeks and then go ahead with the fact that we may have a slightly increased risk of C-section, but that we are willing to accept that in exchange for a decreased risk of stillbirth.

On the other side, if we think that antenatal testing may help to detect that any of those pregnancies that are in trouble, it probably is reasonable to manage these people as the way we would other women who are under 40, and just wait until 41 weeks to induce them.

Read our complete coverage of the Society of Maternal and Fetal Medicine's 32nd Annual Meeting, including:
 
SMFM: LEEP Does Not Increase Risk of Preterm Birth

SMFM: Progesterone Does Not Prolong Pregnancy after Successful Tocolytic Treatment
 
SMFM: Induction of Labor Reduces Trauma Risk for Large-for-Date Fetuses