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 g. Stillbirths were further subdivided into those occurring before labour and those in labour.

RESULTS

We identified 744 897 births from 308 478 women. Of these, 3698 women experienced a stillbirth and, of these, 97.7%, experienced only one. For women with a small-for-gestational- age stillbirth in the first birth, their risk of a subsequent antepartum stillbirth was increased substantially: 4.09%, relative risk (RR) 10.39, 95% CI 5.81-18.59. For women with a first birth appropriate-for-gestational-age stillbirth with no risk factors such as pregnancy induced hypertension, the risk with pre-existing diabetes mellitus or hypertension was also increased but to a much lesser degree (RR 2.46, 95% CI 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.

TWEETABLE ABSTRACT

Stillbirth recurrence is rare.