Stillbirth gestational age as a predictor of recurrence risk

We evaluated risk of subsequent stillbirth (SB) according to gestational age at initial SB.

We retrospectively reviewed a cohort of women delivering a singleton SB with at least one subsequent pregnancy. Relative risks (RRs) were calculated using an initial SB gestational age of 36 to < 40 weeks as the referent. Multivariable logistic regression accounted for potential confounders.

In all, 2,887 mothers and 5,090 subsequent births met inclusion criteria. For the immediately next pregnancy, the linear trend for gestational age was not significant (RR 0.41; 95% confidence interval [CI] 0.03 to 5.53). However, women with index SBs occurring between 20 and 23(6/7) weeks' gestation had a RR for subsequent stillbirth of 2.9 (95% CI 1.2 to 7.1). When including subsequent pregnancies, the test for trend for gestational age was nonsignificant (RR 1.5; 95% CI 0.3 to 8.7). However, women suffering a stillbirth between 20(0/7) and 23(6/7) weeks' gestation in the index pregnancy had an almost threefold increase in the risk of subsequent stillbirth. Women suffering an index stillbirth between 28(0/7) and 31(6/7) weeks' and after 40 weeks' gestation had a 2.5- to 3.5-fold increased risk of subsequent SB.

Gestational age at initial SB predicts risk of recurrent SB. This effect is most pronounced in women with very preterm or with postterm pregnancies.