Risk of Recurrent Stillbirth: A Cohort Study.

OBJECTIVES To evaluate the recurrence risk of stillbirth. DESIGN Retrospective cohort study. SETTING AND POPULATION All births 1992-2017, Alberta, Canada METHODS: Retrospective cohort study. MAIN OUTCOME MEASURES Stillbirth was defined as the death in utero of a fetus with gestational age ≥ 20 weeks or weighing ≥ 500 grams. Stillbirths were further subdivided into those occurring before labor and in labor. RESULTS We identified 744897 births from 308,478 women. Of these 3698 women experienced a stillbirth and of these 97.7%, experienced only one. For women with an small for gestational age stillbirth in the first birth their risk of a subsequent antepartum stillbirth was increased substantially, 4.09% RR 10.39 (5.81-18.59). The risk for women with a first birth appropriate for gestational age stillbirth with no risk factors such as pregnancy included hypertension, and preexisting diabetes mellitus or hypertension was also increased but to a much lesser degree, RR 2.46 (1.23-4.91). For women who had experienced a first birth intrapartum stillbirth the risk of another intrapartum stillbirth was very high, 3.59% RR 36.50 95%CI (20.17-66.05). Most of these births also occurred prior to 24 weeks gestation; 83% (10/12). CONCLUSIONS The risk of recurrent antepartum stillbirth is low. The increase in risk in instances where the antepartum stillbirth was not growth restricted is not clinically meaningful. Given the very low risk in any given gestational week, fetal surveillance is unlikely to be effective and may lead to unnecessary interventions. Intrapartum stillbirth has a very high recurrence risk but may not be preventable.