Science & Sensibility

The headline on a recent BBC News health article reads: “Planned repeat C-sections ‘safer.’ The article goes on to report on two studies that appear to support that conclusion, but do they really? Let’s see what the article says and follow with a look at the actual studies.

One of the studies, the BBC News article tells us, is a U.K. study of 159 cases of uterine rupture in which 139 occurred in women with a prior cesarean. The risk of scar rupture in women with a prior scar, it reports, was seven times greater in women having VBAC labors compared with women planning repeat cesareans, and the risk of the baby dying was three times higher.

That would seem to make a clear case for elective (no medical indication) repeat cesarean (ERC), but if we turn to the study itself, we find that the risk of scar rupture in a VBAC labor was 2 per 1000 VBAC labors versus 0.3 per 1000 planned repeat cesareans, or roughly 2 more scar ruptures per 1000 VBAC labors, not the large difference that “seven times greater” suggests. Moreover, the likelihood of scar rupture was influenced by modifiable factors. The use of prostaglandin, oxytocin, or both for initiating or augmenting labor increased the risk without improving the VBAC rate. In fact, misoprostol was the induction agent in 18% of induced women experiencing scar rupture, but none of the women not having scar rupture were given this agent. ACOG’s 2006 induction guidelines for VBAC labors prohibits using misoprostol because of its strong association with scar rupture. Furthermore, study authors theorize that one reason the scar rupture rate was so low in their study compared with some others was because double-layer uterine suturing, another modifiable practice, is the norm in the U.K..

As for VBAC labor tripling the rate of perinatal (intrapartum + neonatal) death compared with ERC, the study doesn’t give us this number (or maternal morbidity or mortality rates either, for that matter). The study actually only reports maternal and perinatal outcomes in the population overall, which included 20 women with rupture of an unscarred uterus, an event that may be more likely to produce severe adverse outcomes than a scar rupture. In addition, some of the neonatal deaths in women with prior cesarean may have been in women having emergent nonlabor cesareans. For example, three women had a scar rupture in conjunction with placenta previa. The extensive NIH systematic review  of VBAC reported that 6% of babies died as a result of scar rupture in a VBAC labor. We can use that number to calculate the odds of a baby dying in a VBAC labor in the U.K. study by multiplying it (0.06) by the U.K. study’s scar rupture rate (0.002). The result equals 0.00012 or 1 perinatal death per 10,000 VBAC labors. To be sure, every death is a tragedy, but we must also put this into perspective: that mortality is equivalent to the maternal mortality rate with ERC, which is 3 per 10,000, and much less than the fetal loss rate as a result of having an amniocentesis, which one modern-day study found to be 60 per 10,000.

The other study, according to the BBC News article, is an Australian study  of more than 2000 women planning their second delivery after a first cesarean. The BBC article states that the planned VBAC group had more stillbirths, and women were more likely to have severe bleeding, but gives no numbers.

Again, let’s turn to the actual study. The two planned VBAC deaths were unexplained fetal demises in infants born at 39 weeks, the implication being that ERC before that gestational age would have averted them. Perhaps they would have, but as the study  I analyzed in another blog post found, ERC at 39 weeks would have prevented only two of the six antepartum deaths.

The excess in severe hemorrhage (defined as > 1500 ml or transfusion) amounted to 1.5 more instances per 1000 VBAC labors, again, a small absolute difference, and a difference, moreover, that probably would have favored planned VBAC had not so few women had vaginal births. Maternal morbidity mostly occurs in labors that end in intrapartum cesareans, and the VBAC rate in this study was a dismal 43%. With physiologic care, the rate could have been as high as 81%. Even with typical management, studies have reported rates ranging from 61-72% in women with no prior vaginal births. In any case, however worrisome at the time, no differences were found in permanent sequelae such as hysterectomy.

And there is more: neither these studies nor the BBC news article considers the downstream consequences of accumulating cesarean scars, but they should. Even women who plan no more children may change their minds or continue with an unplanned pregnancy. According to the NIH systematic review, as the number of cesareans rises so does the risk of serious neonatal and maternal morbidity and perinatal mortality. By contrast, once a woman has a VBAC under her belt, so to speak, she is almost certain to go on having uneventful VBACs. Also, the review found that the risk of forming dense adhesions (internal scar tissue) rises with number of cesareans as well, thus increasing the likelihood of chronic pain and making any future abdominal surgery, not just future cesareans, more risky and difficult. Add these considerations into the mix, and the balance tips toward planning VBAC as the safer option for almost all women.

Headlines and articles like the one from the BBC News obstruct informed decision making by obscuring the true degree of comparative risk, and the studies contribute by failing to emphasize that better labor management in the previous delivery and current labor would improve outcomes. Planned VBAC is not without risks, but neither is ERC. Women deserve accurate, complete, and, most importantly, quantified information on which to decide on mode of birth after a cesarean. They also should have care in the primary cesarean that promotes safety in future VBACs and care in VBAC labors that promotes safe, healthy vaginal birth. To do less than that does women and their babies a serious disservice.

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Last month yet another study appeared reporting that compared with first vaginal birth, first cesarean increased the likelihood of late antepartum fetal death in the next pregnancy. The study encompassed 10,712 women with one prior birth who had pregnancy duration of 34 weeks or more and were carrying a single, normally-formed fetus. With first delivery via cesarean (22%), the fetal death rate at or beyond 34 weeks’ gestation in the next pregnancy was 2.5 per 1000 compared with 0.5 per 1000 with first birth vaginally, or 2 more late antepartum fetal deaths per 1000 with first delivery via cesarean surgery.

I say “yet another study” because it joins eight others. Six of the eight, one each in Scotland, England , Germany, and Canada and two in Australia, one in South Australia and the other in New South Wales, also reported more late fetal deaths with first cesarean delivery. In two of them, the difference failed to achieve statistical significance, meaning the difference may have been due to chance, but the number of women having a first cesarean was too small to reliably detect a difference. A third study among the six did not perform a significance calculation. The seventh study, conducted in Missouri,  reported an excess among black women but not white women. Mortality rates varied substantially from study to study, but excesses with prior cesarean were similar, ranging from 0.3 to 1.6 per 1000 (mean 1.1 per 1000). The eighth study, a U.S. national study , reported no difference (0.7 per 1000 first cesarean delivery vs. 0.8 per 1000 first birth vaginal) in women with one prior birth, no underlying medical conditions, and a fetus with no structural or chromosomal abnormalities. The gap actually may be wider than appears. Some of the studies restricted analysis to unexplained deaths, which excluded deaths secondary to placenta previa, and accreta and placental abruption, all of which are associated with prior cesarean.

The consistency of this finding is compelling, but you may be thinking that it shouldn’t be surprising because some of the reasons that may lead to cesarean in the first pregnancy would increase the risk of fetal demise in the next pregnancy. Ah, but unlike the other studies, which used population databases, this one was conducted at a single hospital, which means investigators could explore the effect of confounding factors. They found that the association remained statistically significant after controlling for maternal age, height, weight, hypertension, and diabetes, and it strengthened when they confined analysis to women known to have first births to a full-term live infant (n = 4425): 6 per 1000 with first delivery by cesarean versus 1 per 1000 with first birth vaginal, or 5 more late antepartum deaths per 1000 in women with first cesarean delivery in this subgroup. The cause of the excess is unknown, but it would appear that a scarred uterus becomes a less hospitable environment for pregnancy.

Certainly, this risk should not deter performing a cesarean when the health of mother or baby is at stake or everything has been tried, but it seems unlikely that the baby can be born vaginally. However, with one in three first time mothers delivering via cesarean surgery, for many cesareans, clearly, this is not the case. Many cesareans could be prevented with better labor management and by having more patience. As the ninth study concludes, “Our findings reinforce the importance of considering the impact cesarean birth may have on future pregnancies when making decisions regarding method of birth” (p. 16). Amen to that.

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The other day, while looking through my issues of Birth for something else, I ran across a commentary* written by Lamaze teacher Betsy Adrian on why she was leaving the field after five years. She writes:

I realize now that my feelings of burn-out are much more than simply boredom with repeating myself for five years. What lies at the root of my feelings is the conflict between what I believe and what I felt I had to teach. I realized that I have had absolutely no impact on how people have babies. In fact . . . things are worse now for laboring women than when I started five years ago! Fetal monitoring is taken for granted, IVs are always started, almost everyone gets the “deluxe” high-risk treatment, whether they need it or not. . . . The cesarean rate is nothing short of alarming . . . . All of the things that I felt optimistic about early on are actually less likely to occur in a delivery experience now. I believe that childbirth is a unique experience of personal growth for a woman and her partner and that it should take place according to her needs and desires. Birth should never be “routine.” . . . [I]t became ultimately impossible for me to stand up in front of a class and expound on the virtues of fetal monitoring, IVs, being confined to bed, lithotomy position or limited nursing. I can’t do it anymore. I can’t even be “objective” and present both sides of each issue, as I have religiously done in the past. I did not arrive at my opinions irrationally. I read all the pertinent studies in fetal monitoring and IVs . . . and birthing positions. And the evidence is overwhelmingly against these routine procedures. Yet I knew that almost every one of my clients would experience all of these things anyway. I also knew that continuing to teach meant remaining in the good graces of my hospital and that if I became very vocal or militant about my opinions I would lose my source of income. . . . Sadly, I am done with childbirth education. . . . I can’t do it—not if my real purpose has to be to socialize women into accepting poor care, and that’s what we have been doing in too many cases.

Now here is the kicker: this commentary was written 30 years ago. How many childbirth educators could write the exact same commentary today? If a goal of childbirth education is to give women the information and tools they need to make decisions that best promote safe, healthy birth, clearly, we are not achieving it. The “alarming” cesarean rate Adrian cites is 35% at one hospital in her area. Thirty years later, the U.S. national average is 33%, and some hospitals have rates double that or more. Adrian attributes the failure to hospital-based childbirth education, closing with:

My ultimate hope is that childbirth education will move out of hospitals, back into the community where it belongs. Then we can devote ourselves completely to our clients, and not to the doctors and hospitals.

Is the problem simply that educators have to please their employers? I think this is an issue, but not the only one. I taught Lamaze classes independently from 1980 into the 1990s, yet, like Adrian, I quit because I could no longer stand watching my students lie down on the railroad track despite all I could do to tell them there was a train coming. And if hospital-based classes aren’t the only problem, what else is? More importantly, what more could—no, should—childbirth educators be doing about it, including hospital-based educators? What are your thoughts and ideas?

Reference
Adrian BK. Childbirth educator burn-out. Birth and the Family Journal 1981;8(2):101-103.

[Editor’s note: Excerpt from Birth contained in the post is used with permission by the publisher.]

Posted by:  Henci Goer

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As Kimmelin Hull’s recent blog post reported, we have another study to add to the short list (de Jonge 2009); Janssen 2009) of studies of:

1. planned home birth,
2. with a qualified home birth attendant,
3. in women eligible for home birth at labor onset,
4. that had a comparison group of similar women planning hospital birth, and
5. where outcomes were obtainable for hospital transfers.

This study even had the bonus of being prospective, that is, the study was organized ahead of time, as opposed to retrospective, that is, data were collected after the fact from records or surveys. The study’s abstract concludes:

The results support a policy of offering healthy women with low risk pregnancies a choice of birth setting. Women planning birth in a midwifery unit* and multiparous [prior births] women** planning birth at home experience fewer interventions than those planning birth in an obstetric unit with no impact on perinatal outcomes. For nulliparous [no prior births] women, planned home births also have fewer interventions but have poorer perinatal outcomes (p. 1 of 13).

*The study also looked at freestanding and hospital-associated birth centers.

**Women with prior cesareans were excluded.

Let us dig deeper into this conclusion and consider the risk trade-offs between planned home versus planned hospital birth in low-risk first-time mothers.

Investigators created a composite perinatal outcome in order to increase the study’s power to detect a statistical difference in rare outcomes and to evaluate outcomes relevant to intrapartum quality of care. Some of the latter have no permanent or long-term consequences, so I will focus on the ones that do because these would matter most to women deciding where to plan to birth.

Their foremost concern would be, of course, the risk of perinatal death. Investigators report an intrapartum demise plus early neonatal (up to 7 days) death rate of 1.3 per 1000 in nulliparous women starting labor at home (6/4568) versus 0.5 per 1000 in similar women beginning labor in hospital (5/10,626), or a difference of 0.8 per 1000. Confidence intervals overlapped, which means that differences were not statistically significant, i.e. unlikely to be due to chance, but this could be because even populations this large are too small to detect a significant difference in an event that occurs so rarely. Let us assume, though, that the difference is real and that 8 more babies per 10,000 low-risk nulliparous women starting labor at home would die as a result of that decision. To be sure, no excess death rate, however small, is trivial, but to put this into perspective, the excess risk of losing the pregnancy as a result of having an amniocentesis is 60 per 10,000. No one is advising women against amniocentesis on grounds of its danger, so we may conclude that an excess risk considerably more than 8 per 10,000 is deemed tolerable by the obstetric community. Moreover, we have no details about the deaths, so we do not know whether some may have been unavoidable. For example, the study did not include congenital anomalies among its exclusion factors, which means it is possible that a couple who knew their baby would not survive might have chosen to give birth in the privacy and comfort of their home, or a woman might have refused transfer.

The second concern would be outcomes that could result in permanent deficit, which in this dataset were encephalopathy (neurologic symptoms) with no perceptible cause other than hypoxia during labor, and brachial plexus injury (injury to a nerve complex in the shoulder). Here, too, rates in nulliparous women planning home birth (5.5 per 1000) exceeded those with planned hospital birth (3.3 per 1000). Again, differences failed to achieve statistical significance, but, again, this may be because the population was too small to detect one. Assuming the difference is real, 2.2 more babies per 1000 of women beginning labor at home will experience encephalopathy or brachial plexus injury compared with women beginning labor in hospital; however, almost all babies will recover fully, making any difference in permanent injury rates miniscule.

Against perinatal risks must be set the excess maternal risks of planned hospital birth. No woman died, but investigators reported cesarean surgery and anal sphincter injury rates, both of which can result in future or permanent adverse effects.

Rates of anal sphincter injury in nulliparous women were nearly identical (43 per 1000 planned home birth vs. 45 per 1000 planned hospital birth), but differences are likely to be much greater in the United States and Canada, where median episiotomy (cut straight toward the anus) is usual, because, unlike mediolateral (cut angled to one side) episiotomy, the norm in the U.K., median episiotomy strongly predisposes to anal sphincter laceration. Women planning home birth were less likely to have episiotomies (160 per 1000) compared with women planning hospital birth (293 per 1000), which amounts to 133 fewer episiotomies per 1000 women beginning labor at home.

As for cesarean surgery, planning home birth cut the likelihood of cesarean nearly in half. The rate in nulliparous women starting labor at home was 85 per 1000 compared with 160 per 1000 in women planning hospital birth, which calculates to 75 fewer women per 1000 beginning labor at home ending up in the operating room. The consequences of cesarean surgery can be serious for both the current delivery and future pregnancies and deliveries, and the risks include increased likelihood of future maternal and perinatal death. Furthermore, the excess risk of cesarean can be much greater. A large, multicenter Canadian study in women who would have qualified for home birth according to the U.K. study’s criteria reported a cesarean rate of 299 per 1000 in nulliparous women.

So there you have it. For multiparous women with no prior cesareans, planned home birth confers no excess risk. For nulliparous women, it isn’t a matter of risky versus safe but of which risks the woman prefers to run. As the other two high-quality studies conclude, home birth is a reasonable option with the provisos of low-risk status and a qualified attendant.

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A recent New England Journal of Medicine commentator was shocked, shocked, to find that a drug company was price gouging. Joking aside, this is a particularly egregious example of Big Pharma behaving badly. After locking in the right to manufacture 17OHP, K-V Pharmaceutical Company raised the price of treating one pregnant woman at risk for preterm birth by virtue of a prior preterm birth from $300 to more than $29,000, limiting access, according to the commentary, to “the drug’s demonstrated clinical efficiency against a complication for which there are few effective preventive options.”

Why might this be a blessing in disguise? Earlier, I did a blog post, “Does Progesterone Treatment Prevent Preterm Birth? A Case of ‘Skim Milk Masquerades as Cream’”, questioning the effectiveness of progesterone in women with prior preterm birth, including a critique of the trial the commentary cites as demonstrating the effectiveness of intramuscular injections of 17OHP. In that trial, progesterone did not reduce the rate of preterm birth. The rate remained what it had been in similar women before the trial began. Instead, the rate in the control group was much higher than before, and that’s what created the difference between groups. Moreover, the rationale for progesterone is quieting the uterus, but it didn’t do that either. Just as many women in the progesterone group as the placebo group needed treatment for bouts of preterm contractions. Furthermore, another, bigger trial reported no difference in preterm birth rates. So much for “effective.” As I also pointed out in the earlier post, we have no data on the long-term effect of exposing fetuses to weeks of excessive levels of a sex hormone. True, exposure starts after sex organs have developed, but there is more to differentiating boys from girls than looking different, and it is mediated by an ongoing interplay of hormones. The new price barrier could, therefore, protect women and their babies from a treatment that probably doesn’t do them any good and might do their babies harm.

As for lack of preventive options, a social intervention holds great promise. A randomized controlled trial of group prenatal care by midwives (A.K.A. “Centering Pregnancy” ) was published in 2007 in Obstetrics and Gynecology—in other words, hardly buried in an obscure journal. Participants were 1000 women, most of whom were low-income black women, a group at high socioeconomic risk for preterm birth, who were assigned to either group prenatal care or standard care. The preterm birth rate was 14% in the standard care group versus 10% in the group prenatal care group, a one-third risk reduction after controlling for factors that increase risk of adverse perinatal outcomes. In African-American women, the reduction was even more striking: 16% versus 10%. Nothing, nothing anyone ever has tried has reduced preterm birth by a third in a general population.

Why would group prenatal care work? Because preterm delivery is strongly associated with chronic maternal stress. Group prenatal care builds community and helps women feel more competent and confident, as shown by the trial’s other positive outcomes: women in group sessions were less likely to have suboptimal prenatal care, knew more about pregnancy, felt better prepared for labor, were more likely to initiate breastfeeding, and were more satisfied with their prenatal care. With social interventions, everyone wins, not just women spared a preterm birth. Best of all, there is NO downside to group prenatal care, no worries about adverse effects of treatment short- or long-term. As has been said about doula care, another social intervention—which, BTW, is thought to work the same way to reduce cesareans by reducing fear and stress in labor—if group prenatal care were a drug, clinicians would have rushed to obtain it for every hospital pharmacy in the country. And you can bet that providing group prenatal care would cost a lot less than $30,000 per person and probably not even as much as $300, the cost of the cheap version of 17OHP.

Of course it is disappointing that 17OHP isn’t what it’s being cracked up to be. But social interventions have yet to be tried, and at the very least, as the 18^th century French surveyor Cassini de Thury said,

“It is better to have absolutely no idea where one is than to believe confidently that one is where one is not.”

Posted by: Henci Goer

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