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By Henci Goer

Will the baby outgrow the pelvis before she births?

What do we risk by choosing to induce?

The ARRIVE trial is the capstone of a decades-long effort to demonstrate that awaiting labor has no benefits and that inducing labor doesn’t increase cesareans or adverse outcomes and, in fact, that the reverse is true. The argument runs like this: We now know that waiting for labor to start on its own has no advantages over inducing labor, so why risk the baby outgrowing its mother’s pelvis or something going wrong with the baby, which can happen without warning even in healthy women? Is that argument sound?

Are there benefits to waiting for labor to start on its own? Yes. Inducing labor disrupts a complex set of hormonal interactions that prepare the baby for life in the outside world, orchestrate the birth process, help mother and baby cope with the stress of labor, promote successful breastfeeding, and foster attachment between mother and child.

How likely are babies to outgrow their mothers’ ability to birth them with the ongoing pregnancy at term? Not very. The percentage of macrosomic babies (≥ 4,000 g) changes very little over the last few weeks of pregnancy. A study reported that the percentage of macrosomic babies went from 11 percent in week 38 to 14 percent in week 40—and this data comes from a population exclusively of high BMI women, who are more likely to have bigger babies than the population at large.

More important, the inability to birth larger babies largely originates in doctors’ heads, not women’s bodies. Every study that has ever looked at the issue has found that when doctors suspect the baby is going to be big, the odds of cesarean delivery go up markedly regardless of whether the baby is actually on the large side. The reverse is also true: Unsuspected big babies have much lower cesarean rates than babies correctly suspected.

The fear that the baby will be too big for the woman to deliver becomes a self-fulfilling prophecy. It leads to inducing labor to prevent the baby growing even bigger, and induced labors are more likely to end in cesarean. It leads to more diagnoses of failure to progress and failed induction, especially in early labor, before this diagnosis can legitimately be made. Typical medical management practices and policies also load the dice against vaginal birth. Women, in general, are often held to rigid expectations of how rapidly they should progress. Policies that inhibit mobility such as continuous fetal monitoring, routine IVs, encouragement to have epidurals, and requiring women to push and give birth on their backs prevent women from finding activities and positions that promote progress, create more space in the pelvis, and get gravity to work for instead of against them. While this handicaps all women, it hits women with bigger babies the hardest. Finally, requiring women to birth on their backs increases the potential for shoulder dystocia, and when one occurs, doctors are likely to become even more anxious about vaginal birth with a suspected big baby the next time.

Excerpted from

Is Your OB Recommending an Induction at 39 Weeks?

Earlier this year, The New England Journal of Medicine published the ARRIVE study, which found that being induced at 39 weeks lowers the risk of cesarean by 3–4% compared to waiting until at least 40 weeks and 5 days to be induced.

Here’s Why the Study Might Not Apply to You

  • You want to wait until your body goes into labor naturally

    • The ARRIVE study did not exclusively compare people who were induced with people who went into labor naturally. In many cases, it compared people being induced to other people being induced. Participants were either induced during the 39th week of pregnancy or, if they did not go into labor naturally, they were typically still induced at 40 weeks and 5 days. That’s right, the “expectant management” group included inductions.

  • You would not have chosen an induction before hearing about this study

    • Of 22,533 participants eligible to participate in the ARRIVE study, only 27% (6,106) agreed to participate.

  • You are planning to not have an epidural

    • ARRIVE participants were all planning medicalized births, and most had epidurals. The study did not compare people who were planning to birth naturally who were induced with people who were planning to birth naturally who were not induced.
  • You are not birthing at a hospital that participated in the ARRIVE study

    • The ARRIVE study focused exclusively on hospitals using the latest, progressive, long-induction protocols, which have a significantly lower risk of cesarean. These protocols are not standard at many hospitals. Other protocols carry a significantly higher risk of cesarean.
  • You plan to choose your own birthing position

    • The vast majority of ARRIVE participants probably birthed on the bed on their backs, most likely in lithotomy position, based on the general finding that the majority of planned hospital births occur in this position.
  • You do not want continuous monitoring

    • Being induced requires continuous fetal monitoring.
  • Freedom of movement is important to you

    • Induction requires continuous fetal monitoring, which can restrict freedom of movement.

  • You do not want an IV

    • You must have an IV if you are induced with Pitocin.
  • You’re not in your early 20s

    • The average age of ARRIVE participants was 23–24 years of age.
  • You have given birth before

    • The ARRIVE study only included participants who have never given birth before.

The following factors can lower the risk of cesarean by as much as 60%

  • You are focused on lowering your risk of cesarean by more than 3-4%

    • Hiring a doula

    • Having an out-of-hospital birth

    • Choosing a midwife as your provider
    • Laboring or birthing in water