Effect of prior spontaneous preterm birth on delivery timing in subsequent twin pregnancy

People pregnant with twins who had a prior, singleton preterm birth are known to be at risk for preterm birth; however, prior data did not distinguish between spontaneous and iatrogenic births in the prior singleton pregnancy. We aimed to investigate the recurrence risk for preterm birth in a subsequent twin pregnancy in those who had prior spontaneous preterm birth (PSPTB) compared to those without PSPTB in a modern obstetric cohort. This is a secondary analysis of data from a retrospective cohort aimed to evaluate cell-free DNA screening performance in patients with twin pregnancies from 12/2011- 2/2020. We included twin pregnancies >20 weeks gestation and excluded those with nulliparity, unknown pregnancy outcome in twin pregnancy and unknown prior pregnancy history. Presence or absence of PSPTB was confirmed by medical record review. Baseline characteristics, gestational age of twin pregnancy and preterm birth in twin pregnancy were compared between those with history of PSPTB versus those without PSPTB. Multivariable logistic regression was used to assess adjusted odds ratio and adjust for confounders. Of the 958 twin pregnancies, 877 had no PSPTB and 81 had PSPTB. Those with twin pregnancies and prior PSPTB had a higher incidence of preterm birth (PTB) overall (77.8% vs 55.2%, OR 2.84 95%CI 1.66-4.87) and lower gestational age at delivery (34.7 vs 36.6 weeks, p< 0.001) than those with twin pregnancies without PSPTB. However, the rate of spontaneous PTB was not significantly different (46.8% vs 41.7%, OR 1.28 95% CI 0.75-2.17). For patients with PSPTB the adjusted odds ratio for PTB was 3.14 (95% CI 1.72,5.72) after controlling for Black race, body mass index, tobacco use, assisted reproductive technology, chronic hypertension and pregestational diabetes. Pregnant persons who have PSPTB are at increased risk for preterm birth in a subsequent twin pregnancy, and this information may be useful for risk counseling.View Large Image Figure ViewerDownload Hi-res image Download (PPT)