When is it better to induce Mamas on Bedrest?

June 13th, 2012

Labor induction is always controversial. There are times when induction of labor is completely appropriate; when mamas are in crisis with pre-eclampsia or other obstetrical complications, when the baby is struggling or when progression of the pregnancy will put the life of the mother and/or baby at risk. But many mamas are induced for what seems like “convenience”; Mamas are tired, their OB’s want to schedule the delivery so that mama is not delivered by a partner, etc… While many obstetricians advocate for induction as a way to “prevent” adverse outcomes, we can’t ignore the fact that labor induction carries with it an increased risk of intervention in the birth process and adverse outcomes for mama and baby.

Recently in the British Medical Journal, researchers looked at elective inductions to see if they had any benefit on birth outcomes when compared to allowing labor to progress naturally. Sarah J. Stock, PhD, from the MRC Centre for Reproductive Health, University of Edinburgh in the United Kingdom was the lead researcher for the study.

Using Scottish birth and death records, they analyzed data for more than 1.2 million women with single pregnancies who gave birth after 37 weeks’ gestation between 1981 and 2007.

What Stock and her colleagues found is that

There was no significant difference in spontaneous vertex (normal head down) delivery rates between elective induction of labor and the expectant management groups (normal labor progression) for weeks 37, 38, and 39. However, a primary analysis showed an association of elective induction of labor with a reduction in spontaneous vertex delivery rates compared with the expectant management group at weeks 40 and 41. This difference was maintained for week 41, but not week 40, during secondary analysis. (so did more induced mamas have c-sections?? This is what previous data have stated.)

The authors estimate that for every 1040 women having elective induction of labor at 40 weeks, 1 newborn death may be prevented. This would result, however, in 7 more admissions to a special care baby unit (NICU).

The authors conclude that although residual confounding may remain, our findings indicate that elective induction of labour at term gestation can reduce perinatal mortality in developed countries without increasing the risk of operative delivery.

There are a couple of issues that I have with this study. First, while the sample size is definitely adequate, there was no way to control for confounding variables such as maternal size, number of pregnancies, pregnancy complications (i.e bed rest), prenatal state, etc… Additionally, the data has been run through a couple of multivariate analyses which controlled for possible confounding variables. I always wonder, if those “confounders” are incorporated into the data, how do they change the results and conclusions?

The authors conclude that elective induction of labour at term gestation can reduce perinatal mortality in developed countries. Is this reduction in mamas, babies or both? This was not clear to me.

The authors also state that they did not see any increase in operative deliveries.This is very interesting in that the United States has some of the highest c-section rates worldwide and the probability of having a c-section goes up with labor induction. Were these some of the variables removed a confounders?

Finally, the authors estimate that for every 1040 babies born, 1 would be saved from death while 7 would end up in the NICU. Now these aren’t huge numbers, but if you are the mama with the one baby who died, this number is significant. Likewise, it’s not good if your baby ends up in the NICU.

While the authors state that the intention of induction is to reduce perinatal morbidity and mortality in developing countries (and the United States certainly has some of the worst statistics for maternal and infant morbidity and mortality, i.e. maternal and infant complications and deaths, in the developed world) I don’t agree that induction is the way around these potential problems.

Induction of labor initiates a cascade of events that more times than not are not ready to begin. There is a delicate, yet complex interaction between the baby and mama that goes on as the baby begins to enter this world. Both mama and baby’s bodies have to transition from interdependence to independence and for the baby especially, there are several physiological mechanisms that must occur to prepare the fetus (inside baby) to become a neonate (outside baby). Induction speeds up these transitions and in some cases, certain transitions don’t occur (hence the NICU admissions for babies). While some may argue that babies may spend “just a few days” in the NICU, these babies have experienced a traumatic birth, their bodies have not had time to adjust to life on the outside and everyone involved (mama, dad and baby) are all traumatized. Is it really worth it? Further, we can only “guesstimate” gestational age. We really don’t know when the sperm fertilized the egg nor when the embryo embedded in the uterine wall. So a woman we may think is 40 weeks may really be 39  or even 38 weeks. Hence the induction is more of an intrusion. What if she is in fact 42 weeks?

I don’t know what the authors intend to do or recommend with this data, but I hope that they don’t use this data as a way to recommend elective induction as standard of care-especially in low risk uncomplicated pregnancies. I believe that human gestation is intended to be 40 weeks for a reason and that as much as possible, human babies should be allowed to gestate for those 40 weeks. If a baby comes at 38 or 39 weeks, so be it. But if the baby stays in until 40 weeks, are we to assume that there is something wrong or that something will go wrong and intervene?  I believe that babies should be left alone to gestate for a long as they need, and only in the situation of maternal/baby distress or markedly being post dates (say 42 weeks or more) should induction even be an option.

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