Induction at 39 weeks versus waiting for labor

We considered the evidence discussed above in a broader context to develop the following list of potential Pros and Cons of 39-week elective induction.

Induction at 41-42+ weeks versus waiting for labor

Two large randomized, controlled trials on post-term induction came out in 2019. They both found that 41-week induction might improve outcomes for babies.

The INDEX trial from the Netherlands

The trial from the Netherlands is called the INDEX trial, which stands for INDuction at 41 weeks, EXpectant management until 42 weeks (Keulen et al. 2019). It was a multicenter trial, conducted at 123 midwifery practices and 45 hospitals in the Netherlands, where midwives manage most pregnancies and births.

The researchers randomly assigned a total of 1,801 pregnant people to either induction at 41 weeks and 0 to 1 days or to expectant management and induction at 42 weeks and 0 days (if still no labor). In the Netherlands, labor is not usually induced before 42 weeks with an uncomplicated pregnancy, so they were able to get ethical approval to conduct this study. In the U.S., on the other hand, it is not standard practice to continue expectant management for as long as 42 weeks, so it would have been more difficult to get ethical approval to conduct the study there.

Pregnant people were enrolled into the study between 2012 and 2016. Mothers had to be healthy and pregnant with single, head-down babies. Everyone had to have a gestational age that was estimated with ultrasound before 16 weeks of pregnancy. They excluded anyone with a prior Cesarean, high blood pressure disorders, expected problems with the baby’s growth, abnormal fetal heart rate, or known fetal malformations.

In both groups, cervical ripening and induction methods depended on local protocol. This is an important weakness of the study because, like the large Hannah Post-Term trial, individual providers in the INDEX trial may have managed labor inductions differently based on group assignment. The variation in induction methods used in the study also limits the study’s generalizability, or ability to apply the results to the population at large, since care providers lack an induction protocol to replicate.

In the elective induction group, 29% of the participants had spontaneous labor before their induction and 71% were induced. In the expectant management group, 74% of the participants went into labor spontaneously before their planned induction and 26% were induced. Interestingly, the median decrease in length of pregnancy between groups was only two days. In other words, the median pregnancy was only 2 days shorter in the elective induction group, compared to the expectant management group.

What did the INDEX trial find?

For mothers:

There was no difference in Cesarean rates (11% in both groups).

There was no difference in a combined measure of bad outcomes for mothers (11%-14% both groups). This outcome, called the maternal composite adverse outcome rate, included excessive bleeding after birth (≥1000 mL), and/or manual removal of placenta, and/or severe tears, and/or intensive care admission, and/or maternal death. No maternal deaths occurred in either group. The researchers did not report on uterine rupture.

For babies:

Babies in the elective induction group had a lower composite adverse outcome rate (1.7% versus 3.1%). For babies, this combined outcome included perinatal death, Apgar score <7 at five minutes, arterial pH <7.05, meconium aspiration syndrome, nerve injury, brain bleeds, or admission to a newborn intensive care unit (NICU). It was mostly the lower rate of Apgar score <7 at five minutes that contributed to the lower combined adverse outcome with the elective induction group (1.2% with elective induction versus 2.6% with expectant management). The authors note that there was no difference in rates of Apgar score of <4 at 5 minutes; however, the combined outcome was still significantly lower in the elective induction group if using Apgar score <4 at 5 min. and excluding fetal malformations.

One stillbirth occurred in the elective induction group at 40 weeks and 6 days (before the mother was induced) and two stillbirths occurred in the expectant management group (while the mothers were waiting for labor). One was to a first-time mother at 41 weeks and 3 days; her baby was small for gestational age. The other stillbirth was to an experienced mother at 41 weeks and 4 days; her placenta showed signs of infection. There were no newborn deaths in either group. There was no protocol for fetal monitoring (it varied by local guidelines), but fetal monitoring and assessment of amniotic fluid levels was typically performed between 41-42 weeks.



In summary, the INDEX trial found that elective induction at 41 weeks resulted in similar Cesarean rates and fewer overall bad outcomes for babies compared to waiting for labor until 42 weeks. The absolute risk of a bad outcome (a combined measure of perinatal death, intensive care admission, or Apgar score <4 at five minutes) was low in both groups (1.7% versus 3.1%).

The SWEPIS trial from Sweden

The SWEdish Post-term Induction Study (SWEPIS) garnered a lot of media attention with headlines like “Post-term pregnancy research cancelled after 6 babies die.” Indeed, the researchers planned to enroll 10,000 mothers from multiple centers across Sweden but ended up stopping the study early (with about 1,380 people in each group) after their Data Safety and Monitoring Board found a significant difference in perinatal death between the groups (Wennerholm et al. 2019).

In Sweden, just like in the Netherlands, labor is typically not induced before 42 weeks with uncomplicated pregnancies and midwives manage most pregnancies and births. This study set out to compare elective induction at 41 weeks and 0 to 2 days versus expectant management and induction at 42 weeks and 0 to 1 day (if still no labor).

From 2015 to 2018, researchers enrolled healthy mothers with single, head-down babies. Gestational age had to be estimated with 1st or 2nd trimester ultrasound. They excluded anyone with a prior Cesarean, diabetes, low fluid levels, high blood pressure disorders, small-for-gestational-age babies, or known fetal malformations. There is a low stillbirth rate in Sweden, which is why they planned to enroll 10,000 people, but they ended up not needing nearly that many people to see a difference in perinatal outcomes between groups.

A big strength of the SWEPIS trial is that they defined an induction protocol, and the same protocol was used with the people assigned to elective induction and those assigned to expectant management who were induced for medical reasons or because the mother reached 42 weeks of pregnancy. If the mother’s cervix was already ripe, they broke her water and gave her synthetic oxytocin as needed. If the mother’s cervix was not ripe or the baby’s head not engaged, they used any of the following: mechanical methods, misoprostol, prostaglandins, and/or synthetic oxytocin after ripening the cervix first.

In the elective induction group, 14% of the participants had spontaneous labor before their induction and 86% were induced. In the expectant management group, 67% of the participants went into labor spontaneously before their planned induction and 33% were induced. Similar to the INDEX trial, the median decrease in length of pregnancy between groups was very slim—pregnancy in the elective induction group was, in general, only 3 days shorter.

What did the SWEPIS trial find?

For babies:

The study was stopped early after five stillbirths and one early newborn death occurred in the expectant management group, out of 1,379 participants (4.4 deaths per 1,000). Zero deaths had occurred in the elective induction group, out of 1,381 participants. All five stillbirths in the expectant management group occurred between 41 weeks, 2 days and 41 weeks, 6 days. Three of the stillbirths had no known explanation, one was with a baby that was small for gestational age, and the other was with a baby who had a heart defect. The one newborn death occurred four days after birth due to multiple organ failure in baby that was large for gestational age. The author mentions that when complications are present at the end of pregnancy (e.g., with the placenta, umbilical cord, or fetal growth) they may become increasingly important as the days of pregnancy progress, leading to a higher death rate with expectant management past 41 weeks. All of these perinatal deaths occurred with first-time mothers, which suggests that 41-week induction may be especially beneficial for first-time mothers. They found that it only took 230 inductions at 41 weeks to prevent one perinatal death. This is a much lower number than previously thought. If you recall, the INDEX trial did not find a significant difference in perinatal death between the induction group and the expectant management group (1 versus 2 deaths, respectively). This could be because SWEPIS is a larger study and better able to detect differences in rare outcomes like death. It could also be that there was better fetal monitoring of participants between 41 and 42 weeks in the INDEX trial, leading to fewer perinatal deaths. We can’t be certain, because there were no fetal monitoring protocols in either trial. Finally, the participants in the SWEPIS expectant management group tended to give birth a little later than the participants in the INDEX expectant management group, and that might help to explain the higher perinatal death rate in SWEPIS.



There was no difference in the composite perinatal outcome (2.2% to 2.4% in both groups). This combined outcome included perinatal death, Apgar score <7 at 5 min., pH less than 7, brain bleeds, brain injury from low oxygen, convulsions, meconium aspiration syndrome, ventilation after birth, or nerve injury. However, there was a significant difference in perinatal death alone.

The elective induction group babies were less likely to be admitted to intensive care (4% versus 5.9%), they had fewer cases of jaundice (1.2% versus 2.3%), and fewer of them were big babies (4.9% versus 8.3%).

For mothers:

There was no significant/meaningful difference in Cesarean rates (10-11% both groups).

More mothers in the elective induction group had inflammation of the inner lining of the uterus usually due to infection, called endometritis (1.3% versus 0.4%).

More mothers in the expectant management group developed high blood pressure disorders at the end of pregnancy (3% versus 1.4%).

There were no cases of uterine rupture in either group.

Qualitative data found that people in the expectant management group struggled with negative thoughts, and they described feeling in “limbo” while they waited for either labor or a 42-week induction.

As we mentioned, fetal monitoring in this study was done per local guidelines. In other words, there was no study protocol for fetal monitoring during the 41st week of pregnancy. The mothers recruited in the Stockholm region (about half the people in the study) had ultrasound measurement of amniotic fluid volume and abdominal diameter at 41 weeks, whereas such assessments were not regularly performed at the other centers. Importantly, none of the six deaths occurred in the Stockholm region of Sweden, where this type of fetal monitoring was performed. This means that the results of the SWEPIS study may not apply equally to mothers who receive fetal monitoring during the 41st week of pregnancy. Also, since all of the perinatal deaths occurred to first-time mothers, the study results may not apply equally to experienced mothers.

2018 Cochrane meta-analysis on elective induction versus waiting for labor

In a 2018 Cochrane review and meta-analysis, researchers compared people who were electively induced to those who waited for labor to start on its own (Middleton et al. 2018). They included 30 randomized, controlled trials (over 12,000 mothers) comparing a policy of induction at or beyond term versus expectant management. The trials took place in Norway, China, Thailand, the U.S., Austria, Turkey, Canada, the U. K., India, Tunisia, Finland, Spain, Sweden and the Netherlands.

Most of the data (about 75%) came from trials of induction that took place at 41 weeks or later. This meta-analysis came out too early to include the large ARRIVE trial of 39-week induction or the two large 2019 trials (INDEX and SWEPIS) on 41-week induction. The Hannah Post-Term trial, which we will describe in detail, was the largest trial included. The Cochrane authors considered the overall evidence to be moderate quality.

What did they find? A policy of induction was linked to 67% fewer perinatal deaths compared to expectant management (2 deaths versus 16). The Hannah Post-Term trial excluded deaths due to fetal malformations, but some of the smaller trials did not. If we exclude the three deaths from severe fetal malformations, then there was one death in the induction group and 14 deaths in the expectant management group. Overall, the number needed to treat was 426 people with induction to prevent 1 perinatal death. Specifically, there were fewer stillbirths with a policy of induction (1 stillbirth versus 10). The absolute risk of perinatal death was 3.2 deaths per 1,000 births with a policy of expectant management versus 0.4 deaths per 1,000 births with a policy of induction.

A policy of induction was also linked to slightly fewer Cesareans compared to expectant management (16.3% versus 18.4%).

Fewer babies assigned to induction had Apgar scores less than 7 at 5 minutes compared to those assigned to expectant management. There were no differences between groups in the rate of forceps/vacuum birth, perineal trauma, excessive bleeding after birth, total length of maternal hospital stay, newborn intensive care admissions, or newborn trauma.

They were not able to find differences between timing of induction (<41 weeks versus ≥41 weeks) or by the state of the cervix for perinatal death, stillbirth, or Cesarean. The authors concluded that individualized counseling might help pregnant people choose between elective induction at or beyond term or continuing to wait for labor, and that providers must honor their values and preferences. We need more research to know who would or would not benefit from elective induction and the optimal time for induction is still not clear from the research.

The famous Hannah “Post-Term” study

Before INDEX and SWEPIS were published, one of the most important studies that was done on inducing for post-dates is the Hannah et al. 1992 Post-Term study. This study was published in the New England Journal of Medicine.

Because it was such a large study, even larger than the recent INDEX and SWEPIS trials, the Hannah Post-Term study controls most of the findings in the Middleton et al. (2018) meta-analysis described above.

Between the years of 1985 to 1990, a group of researchers enrolled 3,407 low-risk pregnant people from six different hospitals in Canada into the Hannah Post-Term study.

Participants were included if they had a live, single fetus, and were excluded if they were already 3 or more centimeters dilated, had a previous Cesarean, had pre-labor rupture of membranes, or had a medical reason for induction. Unlike the INDEX and SWEPIS trials that induced everyone who had not given birth by 42 weeks and 0 to 1 days, the people assigned to expectant management in the Hannah Post-Term study were monitored as long as 44 weeks. The study took place in the six Canadian hospitals between the years 1985 and 1990.

At around 41 weeks, participants were randomly assigned to either induction of labor or fetal monitoring (expectant management).

In the induction group:

Labor was induced within four days of entering the study (usually about 4 days after 41 weeks).

If the cervix was not ripe (< 3 cm dilated and <50% effaced), and if the fetal heart rate was normal, participants were given prostaglandin E2 gel to ripen the cervix.

A maximum of 3 doses of gel were given every 6 hours. If this did not induce labor or if the gel was not used, participants were given IV oxytocin, had their waters broken, or both. They could not receive oxytocin until at least 12 hours after the last prostaglandin gel dose.

In the monitored (expectant management) group:

Participants were taught how to do kick counts every day and had nonstress tests 3 times per week.

The amniotic fluid level was checked by ultrasound 2-3 times per week.

Labor was induced if the nonstress test was nonreactive or showed decelerations, if there was low amniotic fluid (deepest pocket <3 cm), if complications developed, or if the mother did not go into labor on her own by 44 weeks.

If doctors decided that the baby needed to be born, mothers did not receive cervical ripening—instead, they either had their water broken and/or IV oxytocin, or had a Cesarean without labor.

What did researchers find in the Hannah Post-Term study?

In the induction group, 66% of people were induced, and 34% went into labor on their own before the induction. In the monitoring group, 33% were induced and 67% went into labor on their own.

There were two stillbirths in the group assigned to wait for labor and zero in the group assigned to induction, but this difference was not statistically significant. This means that we can’t be sure if it happened by chance or was a true difference between groups.

The findings on Cesarean rates differ depending on which set of numbers you compare.

You can look at the outcomes for the two original groups—the people randomly assigned to induction and those assigned to fetal monitoring—or you can look at the breakdown of what actually happened to the people in the two groups. In other words, what happened to the people who were actually induced or actually went into spontaneous labor?

What happened in the original, randomly assigned groups?

If you look at what happened in the two original groups (random assignment to elective induction and expectant management groups), the overall Cesarean rate was lower in the elective induction group (21.2% versus 24.5%), even after taking into account whether this was the mother’s first baby, her age, and cervical dilation at the time of study entry.

There was also a lower rate of Cesareans for fetal distress in the elective induction group versus the expectant management group (5.7% versus 8.3%).

But what happened to people who were actually induced or actually went into labor on their own?

If instead of considering the results according to how participants were assigned—to the elective induction and or expectant management groups—you look at what actually happened to the people who were induced or who actually went into spontaneous labor, this is what you will see (Hannah et al., 1996):

So, we see two very interesting things here: people who went into spontaneous labor, regardless of which group they were originally assigned, had a Cesarean rate of only 25.7%. But if people in the expectant management group had an induction, their Cesarean rate was much higher than all of the other groups—42%!

The same pattern holds true when you look at experienced mothers (people who had given birth before):

So what do these numbers mean?

Important details from the Hannah Post-Term study are hidden when you only look at the results according to random group assignment. The reported main findings were that a policy of fetal monitoring and expectant management increases the Cesarean rate.

But a closer look at the findings reveals that only the people who were expectantly managed but then had an induction later in the pregnancy had a really high Cesarean rate. People who were expectantly managed and went into labor spontaneously did NOT have higher Cesarean rates.

One possible explanation for the high Cesarean rate seen in the people who were assigned to expectant management and then ended up getting an induction is that the people in this group may have been at higher risk for Cesarean to begin with, since a medical complication could have led to the induction. The people who were assigned to expectant management and never developed a complication requiring induction were the lower risk people, the ones less likely to give birth by Cesarean.

Another factor that could have contributed to the high Cesarean rate in this group is the issue that we discussed previously—that doctors might have been quicker to call for a Cesarean when assisting the labors of people with medical inductions who had longer pregnancies.

So, if someone is considering expectant management after 41 weeks, one of the benefits is that if they go into labor on their own, they will have a relatively low risk of Cesarean. But one of the risks is that longer pregnancies mean more opportunities for potential complications to show up and if an induction becomes necessary, the risk of a Cesarean with that induction is nearly doubled, from 25.7% to 42%.

Policy of routine induction before 42 weeks is still controversial

The authors of a systematic review from 2019 raise concerns that routine induction prior to post-term puts a large number of pregnant people at risk of harmful side effects from induction (Rydahl et al. 2019a). This review came out too early to include the SWEPIS and INDEX trials.

Unlike the Middleton et al. (2018) Cochrane review, these review authors applied stricter criteria to the studies they included. They restricted the studies to only those published within the last 20 years, with low-risk participants, and comparing routine induction at 41 weeks and 0 to 6 days versus routine induction at 42 weeks and 0 to 6 days. Altogether, they included three observational studies, two randomized controlled trials (RCTs), and two “quasi-experimental” studies (which means they compare groups in a way that isn’t truly random).

Combining the two RCTs with the two quasi-experimental studies, there was one perinatal death in the 41-week induction group and six deaths in the 42-week induction group (a perinatal death rate of 0.4 versus 2.4 per 1,000). The finding was not statistically significant. These same studies showed no difference in Cesarean rates between groups; however, the authors did report that one observational study found an increase in the Cesarean rate with the 41-week induction group.

It remains to be seen whether the INDEX and SWEPIS trial results will lead to changes in national policy in the Netherlands and Sweden to recommend routine induction by 41 weeks instead of 42 weeks.

Back in 2011, Denmark changed its national policy from recommending induction at 42 weeks, 0 days, to 41 weeks, 3 to 5 days. A recently published study compared birth outcomes before the change in policy (2000-2010) versus after the change (2012-2016) (Rydahl et al. 2019b). The study looked back at all births in Denmark between 41 weeks, 3 days and 45 weeks, 0 days of pregnancy. Over 150,000 births were included in the dataset.

They didn’t find any difference in stillbirths, perinatal death, or low Apgar scores comparing the period before versus after the policy change. Perinatal death was already declining before the policy change in 2011, and it continued the downward trend without an additional impact from the 2011 policy change. There was also no impact on the rate of Cesareans or the use of forceps/vacuum.

After the policy change in 2011, however, they did see a significant increase in labor inductions and uterine ruptures. During 2011, the rate of people induced at 41 weeks, 3 days jumped from 41% to 65% and the rate of uterine rupture went from 2.6 to 4.2 per 1,000. The majority of uterine ruptures (73%) occurred among mothers with a previous Cesarean. Unfortunately, we can’t tell from this study whether the uterine ruptures are occurring among people with a prior Cesarean who are being induced—only that the rate of uterine rupture jumped up after the policy change, and that most occurred among mothers with a previous Cesarean.

The researchers expressed concern about the increase in harm without evidence of benefits from a policy of earlier induction. Why did the intervention fail to lower perinatal deaths in Denmark? It could be that the rate was already low in Denmark (and on a downward trend) so there was little opportunity to prevent additional deaths. It could also be that waiting until 41 weeks, 3 days to induce was a few days too late to make a difference. The SWEPIS and INDEX trials found that even a few days after 41 weeks made a significant difference in birth outcomes.

Induction at 41 weeks versus waiting for labor

What about people who are planning a VBAC?

Many people who are planning a vaginal birth after Cesarean (VBAC) are told they must go into labor by 39, 40, or 41 weeks or they will be required to have a repeat Cesarean or induction.

Research has shown that only about 10% of people who reach term will spontaneously give birth by 39 weeks (Smith, 2001; Jukic et al., 2013). So, if a hospital or physician mandates repeat Cesareans for people who have not gone into labor by 39 weeks, this means that 90% of people planning a VBAC with that hospital or physician will be disqualified from having a spontaneous VBAC. Also, some hospitals and providers will not provide inductions with VBACs, which means some people who reach the required deadline will only have one option– repeat Cesarean.

There is actually no evidence supporting hard-stop “must-give-birth-by-39-weeks” or “give-birth-by-4o-weeks” rules for people planning a VBAC.

In 2015, researchers looked at 12,676 people who were electively induced at 39 weeks for a VBAC, or had expectant management for a VBAC (Palatnik & Grobman, 2015).

Elective induction at 39 weeks was associated with a higher chance of VBAC compared to expectant management (73.8% versus 60-62%), but there was also a higher rate of uterine rupture in the elective induction group (1.4% versus 0.4-0.6%).

For people who chose not to be induced, the risk of uterine rupture was fairly steady at 39 weeks (0.5% uterine rupture rate), to 40 weeks (0.6%), to 41 weeks (0.4%).

The first large meta-analysis to specifically look at the link between weeks of pregnancy and likelihood of VBAC was published in 2019 (Wu et al. 2019). It included 94 observational studies with nearly 240,000 people attempting labor for a VBAC. Interestingly, they found that gestational week at birth was not linked to having a VBAC— whether someone gave birth at 37 weeks, 39 weeks, or 41 weeks—it didn’t make a difference to whether someone had a VBAC or a Cesarean birth after Cesarean.

Are there any benefits to going past your due date?

One of the major benefits of going past your due date and awaiting the spontaneous start of labor is the hormonal benefit of experiencing spontaneous labor. In her book Hormonal Physiology of Childbearing (free full text available here: http://bit.ly/14NyRHE), Dr. Sarah Buckley reviewed the research on the hormonal benefits of spontaneous labor.

Based on the available evidence, Dr. Buckley concluded that:

“Overall, consistent and coherent evidence from physiologic understandings and human and animal studies finds that that the innate, hormonal physiology of mothers and babies—when promoted, supported, and protected—has significant benefits for both in childbearing, and likely into the future, by optimizing labor and birth, newborn transitions, breastfeeding, maternal adaptations, and maternal-infant attachment” (Executive Summary, page 9)

Another benefit of going past your due date and experiencing spontaneous labor is that you can avoid the potential risks of a medical induction, which may include experiencing a failed induction (possibly leading to a Cesarean), uterine tachysystole (uterine contractions that are too close together and may decrease blood flow to the baby), and adverse effects of other interventions that often occur with an induction, such as epidural anesthesia and continuous fetal monitoring (NICE Guidelines, 2008).

Although anecdotally it has been said that later term and post-term babies have an easier time with breastfeeding, we were not able to find any research on that subject.

There may be cognitive benefits for babies when the pregnancy continues to 40-41 weeks (Murray et al. 2017). A study of Scottish schoolchildren found that the need for special education was highest among children born before 37 weeks (preterm babies), and then there was a continuous decrease in the need for special education until a low point at 41 weeks, after which the risk quickly rose again (MacKay et al. 2010).

Is it safe for someone to wait for labor to begin on its own, if that is what they prefer? How long is it safe to wait?

When pregnant people go past their estimated due dates, it is appropriate for them and their care provider to discuss the benefits and risks of elective induction and expectant management.

Most research articles and guidelines say that because there are benefits and risks to both options, the pregnant person’s values, goals, and preferences should play a part in the decision-making process.

It is important for expectant families to be aware of the growing research evidence showing worse health outcomes for those who wait for labor after 41 weeks of pregnancy instead of being induced at 41 weeks, especially among first-time mothers and those with additional risk factors for stillbirth.

Ultimately, after receiving accurate, evidence-based information and guidance from their health care provider, pregnant people have the right to decide whether they prefer to induce labor, or wait for spontaneous labor with appropriate fetal monitoring.

How should people and their care providers talk about the risk of stillbirth?

It can be difficult for health care providers and expectant parents to discuss the risk of stillbirth. Research on health care decision-making suggests that one of the best ways to frame the risk of stillbirth is to use the following techniques (Perneger & Agoritsas, 2011; Fagerlin et al. 2011).

Present risks in actual or “absolute” numbers (as opposed to relative risk) Talk about both potential gains and losses Offer a visual if possible Focus on the absolute difference between two risks

So, in a real life situation, this might look like:

“At 41 weeks, out of 10,000 pregnant people, about 17 will have a stillbirth. This means 9,983 won’t have a stillbirth.

In comparison, at 42 weeks, out of 10,000 pregnant people, about 32 will have a stillbirth. This means 9,968 won’t have a stillbirth. Here is a picture to help give you an idea of what this means.

So an extra 15 people out of 10,000 might avoid a stillbirth by being induced at 41 weeks. For the other 9,985 women, it won’t make a difference.”

Then, using a visual aid as we provide below, circle/highlight the additional 15 to show the difference.

Please see our handout on Talking about Due Dates for Providers for tips on how providers can discuss the risk of stillbirth.