Effect of interpregnancy interval after a mifepristone-induced abortion on neonatal outcomes in subsequent pregnancy

The study evaluated effects of interpregnancy interval (IPI) on neonatal outcomes after mifepristone-induced abortion in the first pregnancy.

This observational cohort study, conducted from 1998 to 2001 at antenatal clinics in Shanghai, Beijing, and Chengdu, China, included 4682 nulliparous women with one mifepristone-induced abortion in their first pregnancy, who were enrolled and followed up until delivery. We compared neonatal outcomes among women with different IPIs between their mifepristone-induced abortion and subsequent pregnancy.

When compared to IPI of 18-24 months, there was an increased risk of the neonate being small for gestational age (SGA) [adjusted odds ratio (aOR): 2.01; 95% confidence interval (CI): 1.04-3.88] when IPI was <6 months; this risk was greater among women without a curettage history after abortion (aOR: 2.49; 95% CI: 1.13-5.50). The associations between IPI and preterm delivery (<37 weeks), low birth weight (<2500 g), mean birth weight and ponderal index were not statistically significant.

The results indicate that an IPI <6 months after one mifepristone-induced abortion in first pregnancy is associated with an increased risk of SGA in the subsequent pregnancy.