148: Relationship between interpregnancy interval and perinatal outcome among U.S. women with twin gestations

Abstract

Both short and long interpregnancy intervals (IPI) in women with singleton gestations are associated with adverse perinatal outcomes, yet the relationship between IPI and outcomes in women with twin pregnancies has not been investigated. Our objective was to utilize a population-based cohort to examine differences in maternal and neonatal outcomes of twin gestations based on interpregnancy interval. This was a population-based retrospective cohort study of women giving birth to twins in the U.S. (2012-2014). Inclusion criteria were a twin live birth in the index pregnancy, one prior birth, and available information on IPI. IPI was defined as the number of months (m) from last birth to conception of the current pregnancy. IPI was categorized as 4-17, 18-36, 37-60, or ≥61 months, with 18-36m designated as the referent. Multivariable logistic regression was utilized to assess the independent association of IPI with maternal outcomes, whereas generalized estimating equation models were used for neonatal outcomes to account for clustering. Of 30,889 women meeting inclusion criteria, 8.0% had a 4-17m IPI, 37.2% had 18-36m IPI, 27.6% had a 37-60m IPI, and 27.2% had a ≥61m IPI. Women with the shortest IPI were more likely to be younger, non-Hispanic black, and obese, whereas women with the longest IPI were more likely to have diabetes and hypertension. Women with the shortest IPI had greater odds of cesarean delivery, maternal transport to higher level care, and multiple adverse neonatal outcomes, including preterm birth, birthweight <1000g, ventilation >6 hours, 5-minute Apgar score <4, surfactant use, antibiotics use, and NICU admission (Table). Conversely, women with the longest IPIs had greater odds of adverse maternal outcomes, including gestational diabetes, preeclampsia, cesarean delivery, and maternal transport. Additionally, neonates born to mothers with an IPI ≥61 months were at increased odds of preterm birth, low 5-minute Apgar, and NICU admission. A short IPI preceding a twin pregnancy is associated with largely adverse neonatal outcomes, whereas a long IPI is associated with both adverse maternal and neonatal outcomes. These findings may provide guidance for counseling women with twin gestations.