1. Compared to women who had a live birth in their first pregnancy, women who experienced an initial stillbirth were nearly four times more likely to experience one in their second pregnancy.
2. This increased risk of recurrent stillbirth remained after adjusting for confounding factors.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Stillbirth is a devastating obstetric outcome in which fetal death occurs at more than 20 weeks’ gestation or with a birth weight of at least 400g. While it is believed an increased risk for recurrence of these pregnancy complications exists in subsequent pregnancies, the exact risk is unknown, especially in cases where the cause of stillbirth is unknown. The purpose of this systematic review and meta-analysis was to determine the association between stillbirth in an initial pregnancy and the risk in subsequent pregnancies. Existing relevant studies in the literature were analyzed to total 3.4 million women who had pregnancies beyond 20 weeks. The authors found that compared to women who had a live birth in their first pregnancy, women who experienced a stillbirth in an initial pregnancy were nearly four time more likely to experience one in their second pregnancy, even after confounding factors were adjusted for. However, a similar determination was not possible for women with unexplained recurrent stillbirth due to differences in study methodologies.
This study benefited from comprehensively analyzing the evidence in the literature regarding stillbirth and risk of recurrence. While obesity has been identified as a major risk factor it, there remains uncertainty on the exact factors predisposing the risk of unexplained still birth. However, data was included on over 3.4 million women yielding a robust sample size and generalizability. Inclusion criteria included only analyzing studies from developed nations, but it is not unreasonable to extrapolate a similar outcome in undeveloped nations with less prenatal care. As with all systematic reviews, this study is subject to publication bias and selective reporting with differences in study methodologies. Overall, this study represents the first collective analysis on the particular topic and suggests that the risk of stillbirth is indeed higher in women who experience a stillbirth in their first pregnancy.
Relevant Reading: Stillbirths: the way forward in high-income countries
In-Depth [systematic review and meta-analysis]: This study looked to determine what association existed between stillbirth in an initial pregnancy and the risk of recurrent stillbirth in a subsequent pregnancy. The authors performed a systematic review and meta-analysis, ultimately including 13 cohort studies and three case-control studies that contained 3,412,079 women with pregnancies beyond 20 weeks gestation from high income countries as per the World Bank. 14,283 stillbirths occurred in subsequent pregnancies, 2.5% in women with a history of stillbirth and 0.4% in women with no such history. Compared to women with no history of stillbirth, women who had a stillbirth in an initial pregnancy had an increased risk of stillbirth in subsequent pregnancies (pooled odds ratio 4.83, CI95% 3.77-6.18). After adjusting for confounding factors, this increased risk remained (pooled odds ratio 3.38, CI95% 2.61-4.38). Studies examining recurrent risk of unexplained stillbirth had heterogeneous methodologies precluding a similar determination and analysis.
©2015 2 Minute Medicine, Inc. All rights reserved. No works may be reproduced without expressed written consent from 2 Minute Medicine, Inc. Inquire about licensing here. No article should be construed as medical advice and is not intended as such by the authors or by 2 Minute Medicine, Inc.