Parity and Interval from Previous Delivery-Influence on Perinatal Outcome in Advanced Maternal Age Parturients

To investigate the effect of parity and interpregnancy interval (IPI) on perinatal outcomes in advanced maternal age (AMA) parturients.

A population-based retrospective cohort study of all women older than 40 years, who had a singleton live birth after 24 weeks in the United States in 2017 Women were categorized to three groups by parity and interval from last delivery: primiparas, multiparas with IPI ≤ 5 years, and multiparas with IPI > 5 years. Primary outcome was composite adverse neonatal outcome (preterm delivery <34 weeks, birthweight <2000 g, neonatal seizure, neonatal intensive care unit admission, Apgar score <7 at 5 min, or assisted ventilation >6 h). Secondary outcome was composite adverse maternal outcome and other adverse perinatal outcomes. Univariate and multivariate analysis were used to compare between groups.

During 2017, 3,864,754 deliveries were recorded into the database. Following exclusion, 109,564 AMA gravidas entered analysis. Of them, 24,769 (22.6%) were nulliparas, 39,933 (36.4%) were multiparas with IPI ≤ 5 years, and 44,862 (40.9%) were multiparas with IPI > 5 years. Composite neonatal outcome was higher in nulliparas and in multiparas with IPI > 5 years, in comparison to multiparas with IPI ≤ 5 years (16% vs. 13% vs. 10%, respectively, p < 0.05). Maternal composite outcome was similar between groups. In the multivariable analysis, relative to nulliparas, only multiparity with IPI ≤ 5 years had a protective effect against the composite neonatal outcome (aOR 0.97, 95% CI 0.95-0.99, p < 0.001).

Among AMA gravidas, multiparity with IPI ≤ 5 years has a significant protective effect against adverse neonatal outcomes when compared to nulliparas. Multiparity with IPI > 5 years is no longer protective.