Obstetric Outcomes Across Second to Fourth Labors: Are Low Multiparas Truly Low Risk?

Background: The association between parity and adverse outcomes has been a concern for decades; however, attention to the subgroups of low multiparity has not been adequately studied. Methods: A retrospective study was conducted to examine the differences in maternal and neonatal outcomes among low-level multiparity subgroups, specifically women in their second, third, and fourth labors, who delivered between January 2012 and December 2016. Pregnancy outcomes were compared based on parity (second, third, and fourth labor). Results: A total of 1584 women were evaluated, of which 904 (57%) were in their second labor, 499 (31.5%) were in their third labor, and 181 (11.5%) were in their fourth labor. Women undergoing their second labor were younger than those in their third or fourth labors (29.6 vs. 32.3 or 32.7 years, respectively; p < 0.0001). Moreover, epidural analgesia was more common among women in their second labor compared to women in their third or fourth labor (70.0% vs. 59.5% or 52%, respectively; p < 0.0001). Women in their second labor were more likely to have a longer labor, compared to women in their third or fourth labor (8.50 vs. 7.46 and 6.24 hours, respectively; p < 0.05), and to have a higher rate of cesarean delivery (CD) compared to those in their third or fourth labor (13.2% vs. 7.8% or 6.1%, respectively; both cases, p < 0.01). There were no statistical differences in the rate of adverse outcomes between the third and fourth labor groups. Conclusions: Women in their second labor were more likely to have longer labor durations and a higher risk of CD compared to women in their third or fourth labor. No difference in rates of adverse outcomes was noted between the third and fourth labors.