39-Week Inductions: 6 Things to Consider About the ARRIVE Trial

Why does your OB recommend routine induction at 39 weeks, even if there's no medical reason to end your pregnancy? Well.... there's usually a few factors at play, but one of the most commonly cited reasons is the ARRIVE Trial.

The ARRIVE Trial was a large, randomized, control trial with findings first released at the Society for Maternal Fetal Medicine annual meeting in February, 2018. It compared baby and birthers outcomes when induced at 39 weeks, versus waiting for labor to begin on its own. They found that induction did not result in fewer infant deaths, but did result in "a significantly lower frequency of cesarean delivery".


→ 19% c-section rate when assigned to induce at 39 weeks


→ 22% c-section rate when assigned to wait for labor to begin on its own


Since the trial was published, OBs have largely embraced it, and the majority of our clients report that elective induction was offered to them at 39 weeks. Is it right for you? Read on, for 6 things we recommend you consider when faced with the option of induction.


Note: we're only referring to elective inductions in low-risk people. Elective refers to the induction being the pregnant person's choice, and not done for a medical reason or safety. While some of the considerations below may still be applicable to people facing induction for medical reasons, there is a lot more to think about in that case.


1. Normal Length of Pregnancy

The normal length of pregnancy is 38-42 weeks. In the US, we consider 40 weeks to be our due date and we tend to be surprised when baby isn't here by that date. But due dates should really be considered a range, or a guess. Only 4% to 5% of babies are born on their due date, and only about 50% of first time birthers will give birth before 40 weeks + 5 days (Smith, 2001a).


Even though you're uncomfortable at the end of pregnancy, if you're not in labor yet it means your baby isn't ready to be born. The lungs are the last major organ to finish developing in the womb. While infants are medically considered full term at 39 weeks, we don't know how much they might have benefitted from more time in utero if we induce them before they tell us they're ready.


Americans love things to be on time, scheduled, and speedy. Trust that the end of pregnancy is the exact opposite of everything our culture values. Be patient - I can promise you won't be pregnant forever.


2. Maternal Satisfaction

ARRIVE did not measure whether or not people were happy with their birth. As a whole, inductions are more medicalized than waiting for labor to begin on its own. They include some combination of: IVs, fetal monitoring, induction medications, artificially breaking your water, pain relief meds, longer hospital stays, and more.


If you prefer to avoid medical interventions, an elective induction probably isn't right for you. In fact, ACOG (the governing body for OB/GYNs in the USA) agrees with this. In their clinical guidance regarding the ARRIVE Trial, they write:

"Based on the findings demonstrated in this trial, it is reasonable for obstetricians and health-care facilities to offer elective induction of labor to low-risk nulliparous women at 39 weeks gestation. However, consideration for enactment of this elective induction of labor intervention should not only take into account the trial findings, but that this recommendation may be conditional upon the values and preferences of the pregnant woman, the resources available (including personnel), and the setting in which the intervention will be implemented. A collaborative discussion with shared-decision making should take place with the pregnant woman."

3. Stillbirth Rates

It is important to understand that the risk of stillbirth (the birth of an infant that has died in the womb, after 28 weeks gestation) increases with each week at the end of pregnancy (Muglu et al. 2019). However, the relative risk is low:

Gestation

Stillbirth Rate

Stillbirth Percentage

39 weeks

.42 / 1,000 babies

0.00042%

40 weeks

.69 / 1,000 babies

0.00069%

41 weeks

1.66 / 1,000 babies

0.00166%

42 weeks

3.18 / 1,000 babies

0.00318%

4. Other Ways to Reduce C-Section Risk

ARRIVE showed that the absolute c-section risk lowered from 22% to 19% if you induce at 39 weeks. This is a 16% relative decrease in risk.


Another way to reduce your c-section risk is by hiring a birth doula. ACNM (the governing body for nurse midwives in the USA) suggests using continuous support instead of elective inductions in their response to the ARRIVE Trial publication. With doula support, you reduce your relative c-section risk by 39% AND increases maternal satisfaction (Bohren et al. 2017). You also decrease your likelihood of using unwanted pain medications, and decrease baby's risk of a low 5-min Apgar score.


5. Your Provider's C-Section Rate

ARRIVE found c-section rates between 19% to 22%. This is significantly lower than the national average: 32% (see state by state data from the CDC here). Providers in the ARRIVE Trial followed a specific set of guidelines for slow, successful inductions. The discrepancy between ARRIVE's c-section rate and the national average suggests that most providers are not this patient before calling for surgery.


C-sections are lifesaving, and maternal and infant death rates have decreased since the surgery became more widely used. However, we also know that c-sections are overused and since the 1970s the proportion of birth by c-section has sky rocketed. There's a breaking point where the surgery is no longer done to save lives, but is done out of convenience. We don't know what the ideal c-section rate is, but we do know it's not 0%, and it's also not 32%. The World Health Organization recommends somewhere between 10% and 15% c-section rates to decrease maternal and infant mortality.


Ask your provider what their c-section rate is. Don't take "good" or "average" for an answer - request actual numbers. And since your provider is unlikely to be the one on call when you go into labor, ask about the numbers in their practice as a whole. Hospital culture can also affect your birth. The #1 risk factor determining whether or not you'll have a c-section is the location where you choose to birth. Check out this blog post for the most recent Minnesota hospital cesarean rates (the birth centers and home birth midwives hover between 5% to 15%).


If your provider recommends 39 week induction, ask if they plan to follow the same set of guidelines as the ARRIVE Trial did.


6. Findings Since ARRIVE was Published

In 2022, Gilroy et al. assessed whether there were changes in obstetrical practices and perinatal outcomes in 2019, the year after ARRIVE. They found:

  • 20% increase in inductions

  • 2% decrease in c-sections

  • Increases in: blood transfusions, MICU admissions, need for assisted ventilation at birth, low 5-minute Apgars

  • No difference in NICU admissions nor neonatal seizures

According to the authors, changes in perinatal outcomes "should be explored".


In a separate, observational study, Souter et al. 2022 reviewed data from 23,000+ births around the time of ARRIVE (about 2/3 pre-ARRIVE and 1/3 post-ARRIVE). They found elective inductions and total time spent in the hospital were both higher in the post-ARRIVE group. There were no statistically significant decreases in the rate of cesarean births. The authors concluded that:

"This study suggests that publication of a single randomized control trial (ARRIVE) rapidly influenced obstetric practice resulting in increased elective labor induction among nulliparas. In our population, decreases in cesarean birth and preeclampsia have not been realized raising questions about the applicability of the ARRIVE trial findings to a general obstetric population."

In conclusion....

Induction at 39 weeks is widely considered to be a safe and valid option, and one that many people choose for personal reasons (provider recommendation, concern about raising stillbirth rates, discomfort in late pregnancy, or external factors like moving houses or a spouse starting a new job, etc.).


However, waiting for labor to begin on its own is also a safe and valid option, and one that many people choose for personal reasons (wanting to avoid medical interventions, development of the baby, etc.).


In the end, we can all look at the same data and make different decisions.


If you don't know your options, you don't have any.


Empower yourself to make informed decisions by taking our childbirth education class! Our Lamaze-style class is evidence based, with zero influence from hospital policies. Check out the offerings here: Preparing For Childbirth and sign up today!

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