In February I wrote about new data presented at the Society for Maternal Fetal Medicine annual meeting that showed that elective induction at 39 weeks improves outcomes.
The accompanying press release noted:
Results include:
• Lower rates of cesarean birth among the elective induction group (19%) as compared to the expectant management group (22%)
• Lower rates of preeclampsia and gestational hypertension in the elective induction group (9%) as compared to the expectant management group (14%)
• Lower rates of respiratory support among newborns in the induction group (3%) as compared to the expectant management group (4%)
This was in keeping with previous studies that showed that elective induction decreases perinatal mortality:
[pullquote align=”right” cite=”” link=”” color=”” class=”” size=””]Given the large body of evidence, women who want to be induced at 39 weeks gestation or thereafter should be accorded that option.[/pullquote]
Stock, Sarah J., Evelyn Ferguson, Andrew Duffy, Ian Ford, James Chalmers, and Jane E. Norman. “Outcomes of elective induction of labour compared with expectant management: population based study.” BMJ 344 (2012): e2838.
And studies that showed that induction improves maternal and neonatal outcomes:
Gibson, Kelly S., Thaddeus P. Waters, and Jennifer L. Bailit. “Maternal and neonatal outcomes in electively induced low-risk term pregnancies.” American Journal of Obstetrics & Gynecology 211, no. 3 (2014): 249-e1.
Mishanina, Ekaterina, Ewelina Rogozinska, Tej Thatthi, Rehan Uddin-Khan, Khalid S. Khan, and Catherine Meads. “Use of labour induction and risk of cesarean delivery: a systematic review and meta-analysis.” Canadian Medical Association Journal 186, no. 9 (2014): 665-673.
In other words, contrary to the claims of natural childbirth advocates that babies are “not library books due on a certain date,” there is an optimal time to be born and poor outcomes rise on both sides of that optimal time.
But as I acknowledged at the time, we hadn’t yet seen the completed paper. Yesterday that paper was published in The New England Journal of Medicine titled Labor Induction versus Expectant Management in Low-Risk Nulliparous Women.
They found:
The primary perinatal outcome [a composite score of neonatal injury and death] occurred in 4.3% of the neonates in the induction group and in 5.4% in the expectant-management group (relative risk, 0.80; 95% CI, 0.64 to 1.00; P=0.049 [P
And:
The percentage of women who underwent cesarean delivery was significantly lower in the induc- tion group than in the expectant-management group (18.6% vs. 22.2%; relative risk, 0.84; 95% CI, 0.76 to 0.93; P<0.001). This finding did not change materially after adjustment for previous pregnancy loss. Women assigned to induction of labor were also significantly less likely than women assigned to expectant man- agement to have hypertensive disorders of pregnancy (9.1% vs. 14.1%; relative risk, 0.64; 95% CI, 0.56 to 0.74; P<0.001) and to have extensions of the uterine incision during cesarean delivery …
They concluded:
In summary, we found that elective labor induction at 39 weeks of gestation did not result in a greater frequency of perinatal adverse outcomes than expectant management and resulted in fewer instances of cesarean delivery. These results suggest that policies aimed at the avoidance of elective labor induction among low-risk nulliparous women at 39 weeks of gestation are unlikely to reduce the rate of cesarean delivery on a population level; the trial provides information that can be incorporated into discussions that rely on principles of shared decision making.
Two other recently published papers confirm advantages of induction.
In nulliparous women aged ≥ 35 years, NMII [nonmedically indicated induction] was associated with decreased odds of cesarean delivery at 37 to 39 weeks’ gestation and decreased odds of NICU admission at 40 weeks’ gestation compared with expectant management.
Mathematical modeling revealed that eIOL at 39 weeks resulted in lower population risks as compared to EM [expectant management] with induction of labor at 41 weeks. Specifically, eIOL at 39 weeks resulted in a lower cesarean section rate, lower rates of maternal morbidity, fewer stillbirths and neonatal deaths, and lower rates of neonatal morbidity.
Not surprisingly, midwives who routinely demonize interventions are panicking.
Hannah Dahlen’s reaction is priceless — a whole lot of words that say nothing.
Dahlen, like many other midwives, believes in the faulty Panglossian paradigm that if something is natural, it must be best. In the context of evolution the Panglossian paradigm imagines that everything that exists in nature today is the product of intense natural selection and represents the perfect solution to a particular evolutionary problem.
But as evolutionary biologist Stephen J. Gould pointed out, an existing natural feature may not be the result of evolutionary pressure at all; it may be an incidental feature of a solution to an entirely different problem or it may represent the limits of genetic adaptation.
For example, it would undoubtedly be evolutionarily advantageous to have eyes in the back of our heads yet we never developed them. Instead technology gave us mirrors, which we can use to escape our biological limitations and see behind us. Two eyes don’t represent the best of all possible outcomes, merely the outcome that we have.
In the case of childbirth, each birth involves an evolutionary compromise between the neurological advantages of a larger neonatal brain and the potentially deadly consequences of a larger neonatal brain leading to obstructed labor.
The brain continues to grow throughout pregnancy. Babies born at later gestational ages have bigger heads and are more neurologically mature but also more likely to die in labor. Babies born at earlier gestational ages have small heads which gives them a tremendous advantage in childbirth. The optimal time to be born is when the baby’s head is as large as possible before it becomes too big to fit. That optimal time appears to be at 39 weeks.
The same thing applies to the size of babies relative to the function of the placenta. Some placentas last longer than others. The longer a baby remains inside the mother, the more neurologically mature and fitter it will be. However the longer a baby remains inside the mother, the greater the chance that its growth will outstrip the placenta’s ability to supply oxygen. If the baby stays inside longer than the placenta can function, the baby is stillborn. The optimal time to be born is immediately before the baby’s growth starts to outstrip the placenta’s ability to supply oxygen. That optimal time also appears to be at 39 weeks.
You could make a very good argument that all women should be induced at 39 weeks of pregnancy in order to optimize perinatal outcomes and decrease the C-section rate. No doubt ACOG and other professional organizations will resist that conclusion for the time being. However, given the large body of evidence, women who want to be induced at 39 weeks or thereafter should be accorded that option.
