Thursday, July 21, 2011

Induction Triples the Risk for Cesareans in First-Time Moms

Here is the abstract of a recent study (Thorsell 2011) on how induction of labor increases cesarean rates, especially in first-time mothers with an unripe cervix.

This is yet another reason why the very high induction rate in women of size plays such a strong role in the higher cesarean rate in "obese" women.

[For example, in Abenhaim and Benjamin, 2011 about 50% of "morbidly obese" women were induced; double the 24% rate in "normal BMI" women.  In addition, more than half of the "morbidly obese" women had a very unripe cervix (dilation of 2 or less) upon admission.  Is a high cesarean rate in this group therefore any surprise?]

In the Thorsell 2011 study (abstract below), first-time mothers with an unripe cervix who were induced had a 42% c-section rate in labor.  Yes, you read that correctly; nearly half ended up with a cesarean.  After controlling for other factors, inducing labor in a first-time mother with an unripe cervix tripled her risk for a cesarean.

The effect was much less strong in multips, whose cesarean rate after induction was a more modest 14%.  Yet, after controlling for variables, their risk was still nearly doubled.  So while the total numerical rate was much lower in multips, the odds ratio was still considerably increased.

Of course, it's important to point out that induction, even in a first-time mother, results in more vaginal births than cesareans.  If you are induced, it doesn't mean that a cesarean will automatically follow; you still have a reasonable chance for a vaginal birth, especially if your cervix is ripe first or if you've had a previous vaginal birth.

But the risk for cesarean is greatly increased when labor is induced, and especially so in a first-time mother whose cervix is not very ripe.

How many of these cesareans could be avoided just by being a little more patient? 

And how many cesareans in women of size could be avoided by refraining from induction until the cervix is very ripe, or by awaiting spontaneous labor as much as possible?

Acta Obstet Gynecol Scand. 2011 Jun 17. Induction of labor and the risk for emergency cesarean section in nulliparous and multiparous women. Thorsell M, Lyrenäs S, Andolf E, Kaijser M.  PMID: 21679162

Division of Obstetrics and Gynecology, Department of Clinical Sciences, Karolinska Institutet, Danderyd Hospital, Stockholm, Sweden, and Clinical Epidemiology Unit, Department of Medicine at Karolinska University Hospital and Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.

Objective. To assess the risk for emergency cesarean section among women who were induced to labor in gestational week ≥ 41 and to evaluate if parity and mode of induction affected this association.

Design. Hospital based retrospective cohort study.

Population: Singleton pregnancies delivered after ≥41 gestational weeks at Danderyd Hospital, Stockholm, Sweden during 2002-2006.

Material and Methods. Of 23 030 singleton pregnancies meeting the entry criteria, 881 were induced with Bishop score of < 7. Obstetric outcome was assessed through linkage with the Swedish Medical Birth Registry and a local obstetrical database containing information from patients' medical files. Results were adjusted for BMI, age and the use of epidural analgesia.

Main outcome measure. Risk for emergency cesarean section.

Results. Among women who were induced, the proportions delivered by emergency cesarean section were 42% for nulliparous and 14% for multiparous. Compared to spontaneous onset, this corresponded to a more than threefold increase in risk for nulliparous women (OR 3.34, 95% CI 2.77-4.04) and an almost twofold increase in risk for multiparous women (OR 1.94, 95% CI 1.24-3.02). There was no significant difference in risk for emergency cesarean section between the two methods of induction (PGE(2) and transcervical catheter).

Conclusion. Compared to spontaneous onset of delivery, induction of labor is associated with an increased risk for emergency cesarean section both among nulliparous and multiparous women. When labor is induced the high risk for emergency cesarean must be kept in mind.



Evenspor said...

I read something a while back (unfortunatley, I don't know whether the source was reliable) that said that first-time mothers, on average, give birth 10 days after their due date.

It's a shame that they're very rarely told that and that so many doctors are too impatient to allow labor to start on it's own or continue on it's own. What I have seen is that even when an induction in a first time mom doesn't result in a c-section, it often leaves them believing they are not capable of giving birth by themselves. I have heard women say, "I can't give birth to big babies," or, "I can't give birth without someone breaking my bag of waters for me," when really they had difficulty because of an induction or they simply have never had the chance to find out.

I think it's very sad that women have that confidence in their bodies taken away from them.

Janie said...

how come when I try to nicely tell first time moms this - people think I am being harsh?

Anonymous said...

This is important information for moms to know and I like how you presented it. Induction on an unripe cervix definitely increases the c-section risk. That said, the risk has to be weighed against the risks inherent in continuing to go post dates. As a (hopefully) soon to be first time mom and having seen the chart showing the increase risk of neonatal death the further post dates you go, I know I personally would rather risk the c-section than risk the stillbirth at greater than 41 weeks. That's a deeply personal decision though, and the more information about real risk and pros and cons, the more empowered we are to make whatever choice fits our family best.

Selena said...

I agree with Evenspor. It's sad that women think a due date is like an expiration date and the baby must come out as soon as possible. It's even more sad when you consider that due dates are not an exact science and can be off by days or even weeks. With my last baby I carried him for 42 wks 2 days until I spontaneously went in to labor and he was born perfectly healthy. Luckily for me I tracked my cycles and knew my ovulation date as it put my due date a full week later. If I had gone by my last cycle I would have been considered past 43 weeks. Just think of how many babies are not even as far along as everyone thinks and are forced out early. I know my first three children were and wish I had known better for them. I'm also one of those women who as a first time mom was induced successfully and thought I'd never labor without help. Which led to a cbac with my third since I agreed to be induced thinking I'd never labor on my own.

To Anon--I would do a little more research on still birth past 41 wks if I were you.

Anonymous said...

I ended up with an induction 5 weeks ago. The idea of it broke my heart, but to the day I was induced, at 42 weeks exactly, I really wasn't having any contractions at all. There was very little chance I wasn't as far along as they said; in fact, chances were better that I was actually farther along. I think I ended up as the outlyer for most statistics though. Here's the list of reasons where, under different circumstances, I probably would have been pressured into a c-section.

- I am categorized as "morbidly obese"
- I was induced at 42 weeks, to the day
- Labor from start to finish was about 32 hours
- By the time I started pushing (which ended up only being about 10-15 minutes), my membranes had been ruptured about 24 hours (ruptured by midwife)
- DD was born at 9lbs, 2oz, so "big"
- When DD decided it was go time, I was still only at 6cm, which I had been for at least 18 hours

Everyone I know was SHOCKED that the midwives "let me" go to 42 weeks, however, they standard is not to induce until 42 weeks unless medically necessary.

Thankfully, the midwives, particularly the on call one that ended up delivering DD, was very very VERY supportive and I ended up with a vaginal birth. It was as natural as it could get, considering the induction, with no pain medications. Going into it, I was miserable, I felt like a failure because my body was showing no signs of going into labor at all. It was all the more frustrating because my pregnancy was pretty much complication free.

I realize that if I had a different provider, or even if a different midwife was oncall, I most likely would have ended up with a c-section. I even had the anesthesiologists trying to convince me to put the epidural, sans the medication, in "just in case" because they felt they might not be able to trach me "if" I needed a c-section. The worst part was, the ones that felt this way didn't even have the gall to discuss it with me, they went through the midwife (who disagreed with their assessment, as did a later anesthesiologist).

As much as giving birth to my daughter left me with a huge sense of empowerment, I still have that nagging feeling of, what if my body just can't jump start labor on its own? What if for the next baby, I'm not as well supported? It's amazing how your care provider can make all the difference in the world. In my case, my labor completely turned around at the shift change. Had the previous midwife still been on call, I'm not sure I would have had the same outcome.

Sorry for the long reply. I just wanted to share my experience.

Elizabeth said...

Evenspor, I completely agree with you as well. Managed labor really does sap a woman's confidence. Or at least it did mine. I fit into that 42% of first time mothers who were induced who ended up with a c-section. I personally believe that God designed a woman's body to give birth, and yet it seems like I couldn't. BUT maybe if my ob would have been willing to let DD be born without any outside interfence, maybe I could have. I don't know, and unfortunately with the way women who want VBAC's are treated, I'm probably going to have to fight to find out if my body works.
Selena, the whole concept of due date as an expiration date is, I think, the problem. As soon as I reached my due date my ob started in on when are we going to induce. Though I guess I'm lucky since I was able to put him off until after I was past 41 weeks, bit still.
Janie, I have no idea if you come across as harsh or not in real life, but I don't think trying to point these things out to first time moms is a bad idea. I was aware of the statistics that inducing increase your risk of a c-section, and yet I still let myself be talked into an induction using drugs (Cytotec) that I wasn't at all comfortable about, and then let myself be scared into a c-section. I had this weird feeling the day of the induction that I was going to end up with a c-section, but I never really seriously considered that I would have anything but an unmedicated natural birth until I was signing the consent forms for the spinal and the surgery. Heck, to be perfectly honest, I don't care if it does come across as harsh. As long as the Cesarean rate is 30ish%, and higher if you're induced, I wish I would have had someone there pointing things out every step of the way and being an advocate for me to prevent things happening.

Birthkeeper said...

Anonymous #1: The risk of stillbirth does not dramatically rise at 41 weeks. That statement is based on outdated research (McClure-Brown study) from over half a century ago! The literature actually shows increased perinatal mortality only after 43 weeks gestation. See Gail Hart's excellent article "Induction and Circular Logic" for details.

Furthermore, Mittendorf et. al. determined that for a first-time pregnant (primigravid) caucasian woman, the AVERAGE length of gestation is 41 weeks + 1 day. That's the center of the bell curve.

Let's stop fear-mongering and work with the facts, please.