Labor duration tied to adverse outcomes during second-trimester medication abortion

Key takeaways:

• Women with longer vs. shorter labor duration had greater maternal morbidity.
• Maternal morbidity frequency increased by 0.47% for every 1-hour increase in labor duration.

Labor duration was independently associated with risks for adverse maternal outcomes, specifically intraamniotic infection, during second-trimester medication abortion, according to study results published in Obstetrics & Gynecology.

“A key cause of complications during term labor inductions is the duration of labor, defined as the time from initiation of labor to delivery. Data demonstrate that time spent during labor is proportional to the frequency of maternal morbidity such as clinical chorioamnionitis and postpartum hemorrhage,” Ashish Premkumar, MD, PhD, assistant professor in the department of obstetrics and gynecology at the Pritzker School of Medicine at the University of Chicago, and colleagues wrote. “To date, investigators have yet to evaluate whether the relationship between duration of labor and adverse health outcomes holds in the setting of second-trimester medication abortion.”

Premkumar and colleagues conducted a retrospective cohort study of 681 women from four centers in Cook County, Illinois, with singleton gestation who underwent second-trimester medication abortion from 2009 to 2019. All women had no evidence of advanced cervical dilation, rupture of membranes or preterm labor. Researchers evaluated the relationship between labor duration, defined as hours spent from misoprostol administration to fetal expulsion, and adverse outcomes.

Primary outcome was composite morbidity, defined as uterine rupture, need for blood transfusion, clinical chorioamnionitis, ICU admission or need for hospital readmission.

Overall, median duration of labor was 11 hours and 19.2% of women experienced composite morbidity.

Women who experienced longer labor duration had higher frequency of composite morbidity compared with women with shorter labor duration (31.2% vs. 14.9%; P < .001). When researchers assessed labor duration as a continuous exposure, composite morbidity frequency increased by 0.47% for every 1-hour increase in labor duration. Women with the highest quartile of labor duration of 17 hours or longer had a statistically higher risk for experiencing morbidity vs. women in other quartiles (adjusted RR = 1.99; 95% CI, 1.34-2.96).

Clinical chorioamnionitis was the only component of composite morbidity that was higher for women with longer vs. shorter labor duration (26.2% vs. 10.6%; P < .001).

In the post hoc subgroup analysis of gestational age quartile, gestational age was not associated with composite morbidity risk. In addition, homogeneity tests showed no significant difference in morbidity risk for women based on parity or uterine scarring history.

“Further studies should focus on interventions to reduce labor duration and, subsequently, morbidity incurred during second-trimester medication abortion,” the researchers wrote.