Recurrence risk of preterm birth in subsequent twin pregnancy after preterm singleton delivery

Objective To determine the risk of preterm birth in a subsequent twin pregnancy after previous singleton preterm birth. Design Cohort study. Setting Nationwide study in the Netherlands. Population In all, 4071 nulliparous women who had a singleton delivery followed by a subsequent twin delivery between the years 1999 and 2007 were studied. Methods Outcome of subsequent twin pregnancy of women with a history of preterm singleton delivery was compared with pregnancy outcome of women with a history of term singleton delivery. First deliveries were subdivided into iatrogenic and spontaneous preterm deliveries. Furthermore analyses were performed by subgroups for gestational age at the time of singleton delivery. Main outcome measure Spontaneous preterm birth (<37 weeks of gestation) in subsequent twin pregnancy. Results In the index singleton pregnancy, preterm birth occurred in 232 (5.7%) of 4071 women. The risk of subsequent twin preterm birth was significantly higher after previous singleton preterm delivery (56.9 versus 20.9%; odds ratio 5.0; 95% CI 3.8-6.6). Risk of subsequent twin preterm birth was dependent on the severity of previous singleton preterm birth and was highest after preceding spontaneous instead of iatrogenic singleton preterm delivery. Conclusion Preterm birth of a singleton gestation is associated with an increased risk of spontaneous preterm birth in a subsequent twin pregnancy.