What are the risks of pushing for longer periods of time?

Due to the large amount of research on this topic, we limited our review to studies that have been published in the past ten years. Since 2007, there have been seven observational studies and one randomized trial on the length of pushing (Cheng et al. 2007; Allen et al. 2009; Laughon et al. 2014; Cheng et al. 2014; Hung et al. 2015; Altman et al. 2015; Grobman et al. 2016; Gimovsky & Berghella, 2016). Below, I have provided a brief summary of the observational research and described the findings from the one randomized trial.

Observational studies

In the seven observational studies that have been published on the length of pushing since 2007, several findings were consistent across the studies.

First, researchers have repeatedly found that people with epidurals have much longer pushing times than those without epidurals. For example, one study found that half of all first-time mothers without an epidural gave birth by the time they reached 47 minutes of pushing. But when they looked at first-time mothers with an epidural, it took 120 minutes (two hours) of pushing for half of the people to give birth—the other half took longer. When they looked at the 95th percentile (the length of the second stage by which 95% of those pushing had already given birth, considered the upper range of normal), 95% of first-time mothers without an epidural gave birth within 3 hours and 17 minutes, while 95% of first-time mothers with an epidural gave birth within 5 hours and 36 minutes! (Cheng et al. 2014).

It’s encouraging to note that in research studies, the majority of people with longer pushing times still ended up with vaginal births. However, evidence shows that the longer someone pushes, the more likely it is that they will experience a Cesarean birth or forceps- or vacuum-assisted birth.

Researchers also consistently found that longer pushing times are related to higher chances of problems for the mother. For example, first-time mothers with an epidural who pushed more than three hours had postpartum hemorrhage rates of 5.9%, compared to 3.7% in those who pushed less than 3 hours. Infection of the uterus also went up with prolonged pushing in first-time mothers (1.2% vs. 0.4%), and the 3rd or 4th-degree tear rate also went up (10.1% vs. 5.8%). However, it’s not clear whether the higher rates of these complications are due to the prolonged pushing phases themselves, or because of the higher rates of intervention that happen with longer pushing phases or both. For example, the higher use of forceps or vacuum could contribute to the higher rates of severe tears (Laughon et al. 2014).

For babies, longer pushing times have been related to higher rates of NICU admissions, low Apgar scores, and other newborn health problems. However, the overall rate of these complications is low. For example, in one study that looked specifically at experienced mothers, babies born after three or more hours of pushing had a NICU admission rate of 5.4%, compared to 2.9% in babies who were born after less than one hour of pushing. Several researchers stated that their results support the new guidelines—that people should have additional time to push, because rates of vaginal birth are high and overall complication rates are low (Allen et al. 2009; Laughon et al. 2014; Cheng et al. 2014).

One researcher pointed out that any decision about whether to push for longer periods of time or not should take into account the benefits and risks for each woman’s unique situation. Some examples of individual factors that may influence the decision include how well the baby is handling the pushing, how much the baby has traveled down into the pelvis, and if the baby is continuing to descend with pushing efforts (Grobman et al. 2016).

Randomized controlled trial

In 2016, Gimovsky et al. carried out the first randomized trial on the length of the pushing stage. This was a small study (78 women) that took place in 2014 to 2015 at a single hospital in Pennsylvania. Women could be in this trial if they were having their first baby (single baby, head-first position at term), and if they had normal fetal heart monitor results during labor. If women reached the three-hour pushing phase mark with an epidural, they were randomly assigned (like flipping a coin) to either an “extended care” group (41 women) or a “usual care” group (37 women). Those in the extended care group were given the option of continuing pushing for one additional hour, in line with the new ACOG/SMFM guidelines. Women in the usual care group were given no additional time to push. In both groups, when a woman’s time was up, she gave birth with either Cesarean, vacuum, or forceps. (Gimovsky & Berghella, 2016)

It’s important to note that this study only included women with epidurals. Women without epidurals all either gave birth before three hours of pushing or declined to be in the study. Those who were included, then, all had medically managed labor and births: all of the women had epidurals, about half of them were induced (43-54%), and most of them had labor augmented with Pitocin (81-83%). Most women (81-83%) were also instructed to delay pushing for about an hour because they did not have an immediate urge to push once they were fully dilated. This delay was included in the total time they were given for the pushing phase. Typical practice in this hospital was to instruct those pushing to hold their breath while pushing, and most women pushed while lying on their backs (93-97%). There was a low crossover rate between groups. Two women who were assigned to the extended group received usual care, and nine of those in the usual care group had extended care.

The researchers found that women in the extended-time pushing group had a much lower Cesarean rate than individuals in the usual care group—19.5% vs. 43.2%. The researchers estimated that for every four women who received an additional hour during pushing, one woman would avoid a Cesarean. Rates of spontaneous vaginal birth (giving birth vaginally without the help of vacuum, or forceps) were also much higher in the extended care group (51.2% vs. 18.9%). The study was too small to tell differences in postpartum hemorrhage, maternal infection, severe tears, and NICU admissions—however, NICU admission rates were high in both groups (32% and 38%).

According to the author, the reason the overall NICU rates were high is that this particular hospital admits every baby to the NICU whose mother had suspected chorioamnionitis, (personal communication, Dr. Gimovsky, July 2016). Although the definition of suspected chorioamnionitis (infection of the fetal membranes) was not clarified, it could mean that any mother with a temperature above a certain number could be seen as having suspected chorioamnionitis (even if the fever simply related to having an epidural—a known common side effect of epidurals). This study also had high rates of 3rd and 4th-degree tears (ranging from 3% to 14%), and chorioamnionitis (27% to 35%), but with no statistical differences between groups. There were zero cases of newborn blood infections, seizures, or deaths.