Prolonging the Second Stage of Labor can Have Negative Effects on Mom and Baby

Did you know that there are three stages of labor?

It’s true. The first stage of labor refers to the period between the onset of labor and the point when a woman’s cervix is dilated to 10 centimeters; the second stage is the period between when the woman’s cervix is dilated to 10 centimeters and the delivery of the baby; and the third stage is the delivery of the placenta (1). In this piece we will be focusing on the second stage, and what constitutes dangerously prolonged labor.

In the second stage of labor, the cervix is fully dilated, and the woman needs to push the baby out. The second stage of labor can last between 20 minutes and 2 hours (1).

A February 2019 study set out to analyze the effects of prolonging the second stage of labor on the rate of cesarean delivery and maternal and fetal outcomes (2). Researchers did this by studying medical records from births during  two different periods. The first period was between May 2011 and April 2014, and the second was between May 2014 and April 2017.

These two periods were chosen because in 2014, the American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) agreed to allow an additional one hour of extended pushing in the second stage of labor for nulliparous and multiparous women before diagnosing second-stage arrested labor (2).

In the first period studied, second-stage arrest was defined in nulliparous women as occurring after three hours with regional anesthesia and two hours without it; it was defined in multiparous women as occurring after two hours with regional anesthesia or one hour without it. In the second period studied, the second stage of labor was allowed to continue for an extra hour in both multiparous and nulliparous women.

The research showed that there was a decrease in the rate of cesarean delivery. For nulliparous women in the first period, the rate of cesarean section was 23.3%; in the second period it was 15.7%. For multiparous women in the first period, the rate of cesarean section was 10.9%; in the second period it was 8.1%. So with an extended second stage of labor, cesarean delivery proved to be less likely.

This study shows, however, that with a prolonged second stage of labor, the maternal and neonatal outcomes were not as good as they had been with a shorter second stage of labor. In fact, rates of shoulder dystocia, rates of third- and fourth-degree laceration, and rates of admission to the neonatal intensive care unit (NICU) were all higher in the second period than in the first.

Overall, prolonging the second stage did successfully lower the number of C-section deliveries administered. It had negative health effects on mother and baby, however, so more studies are needed to improve these outcomes.

Sources

  1. 2nd Stage of Labor. (2017, September 26). Retrieved May 3, 2019, from https://americanpregnancy.org/labor-and-birth/second-stage/
  2. Zipori Y, Grunwald O, Ginsberg Y, et al. The impact of extending the second stage of labor to prevent primary cesarean section on maternal and neonatal outcomes. Am J Obstet Gynecol 2019;220:191.e1-7.

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