The obstetrics world is ablaze with studies, recommendations, and opinions about the second stage of labor- the pushing period during labor. Likewise, the Women’s Health Review blog has recently featured two articles on the second stage of labor. I now write with yet another perspective from Drs. Leveno, Nelson, and McIntire of the University of Texas Southwestern Medical Center, who express their concern for infant safety in light of a longer second stage of labor.
On April 5, I wrote about a randomized trial on the length of the second stage of labor in which women who were allowed to push longer had fewer c-sections, but women also had more postpartum hemorrhages and severe vaginal tears. On April 19, I wrote about an observational study by Grobman et al. showing that the majority of women who pushed for longer than recommended did achieve a vaginal delivery. In that study the incidence of infant complications increased over time, but these complications affected a small percentage of infants: about 1% or less.
Perhaps my favorite part of this new opinion article is their brief history of the second stage of labor, giving us all a perspective on how we arrived at our current recommendations and standards. The first recommendation came from Dr. Whitridge Williams, who authored the standard obstetrics textbook that has stood the test of time for over a century (with updates, of course). In 1903, Dr. Williams published his observation that pushing for longer than 2 hours seemed to lead to increased injury to mother and infant. In 1952, Drs. Hellman and Prystowski published a study that showed more infant deaths when the second stage lasted longer than 2.5 hours. In 1977, Dr. Cohen added the benefits of electronic fetal monitoring to a new study, that supported allowing the second stage to continue beyond 2 hours if the fetus showed no signs of distress. In his study, APGAR scores were lower for infants with a second stage longer than 3 hours. In the 1970’s, epidurals were becoming more commonplace. Dr. Cohen’s research showed that a lot of women with epidurals gave birth vaginally between two and three hours when they had an epidural. Thanks to his research, the recommendations changed in 1989 to allow an extra hour of pushing if an epidural was in play.
Current Evidence on Safety
Fast forward to the 21st century and we see an influx of new research pushing the boundaries of the second stage of labor. Why the sudden interest in pushing longer? The cesarean section rate rose to an all-time high of 32.9% in 2009, causing OBGYNs everywhere to search for ways to reduce this rate. As I addressed in my previous blog posts, labor management is a balancing act. When are we actually causing more harm than good by doing all these c-sections? Six studies have explored how babies fared after 3 hours of pushing. The studies showed increased infant trauma, need for the Neonatal ICU, stillbirth, death, brain injury, low APGAR scores, seizures, needing a breathing tube, and asphyxia. However, three of these studies included an interesting statistical trick. They “controlled” for mode of delivery- whether the infant was ultimately delivered by cesarean delivery or vaginal delivery. When they performed this statistical trick, the differences in complications disappeared. However, the astute authors of this interesting opinion article point out- isn’t the c-section a result of the long labor, not something to make disappear with statistics?
In light of the newest evidence, especially the studies that showed no harm to infants when controlling for mode of delivery, the major OBGYN groups changed their recommendations to allow longer second stages of labor. For instance, now first-time moms with an epidural can push for over 4 hours. Dr. Leveno and his colleagues voice their very serious concern that the new recommendations will lead to more injuries to infants. Their well-reasoned opinion article has certainly made me think twice about safety of the second stage of labor. I look forward to seeing how leaders in the field incorporate this evidence into the recommendations for balancing the risks of childbirth to create the safest environment possible for mothers and babies.