Gestational age of previous twin preterm birth as a predictor for subsequent singleton preterm birth

Objective: We sought to determine an optimal gestational-age cutoff of preterm twin deliveries for predicting subsequent singleton preterm birth (PTB).

Study design: We performed a retrospective study of women with a spontaneous twin delivery who subsequently had a singleton gestation. Univariate and multivariate analyses determined the risk of a spontaneous singleton PTB after a PTB of a twin gestation. Different gestational-age cutoffs of the previous twin PTB were evaluated.

Results: Among 255 women, previous twin PTB at <34 weeks' gestation was associated with an increased risk of singleton PTB (odds ratio, 9.67; 95% confidence interval, 3.07-30.47). Every twin gestational age cutoff at <34 weeks' gestation had a significantly higher risk of subsequent singleton PTB, which was no longer significant at ≥ 34 weeks' gestation (odds ratio, 1.68; 95% confidence interval, 0.23-12.19).

Conclusion: In women with a previous spontaneous twin PTB at <34 weeks' gestation, there is an increased risk of subsequent singleton PTB. A twin birth at ≥ 34 weeks' gestation is not associated with an increased risk for a subsequent singleton PTB.