Placental abruption and adverse perinatal outcomes

Context Pregnancies complicated by abruption result in increased frequency of perinatal death and decreased fetal size and gestational duration, yet the extent of placental separation and its effect on these adverse outcomes is unknown. Objective To assess the contribution of placental abruption and extent of placental separation to stillbirth, preterm delivery, and fetal growth restriction. Design Hospital-based, retrospective cohort study. Setting Mount Sinai Hospital, New York City, NY. Participants A total of 53 371 pregnancies occurring in 40 789 women who were delivered of singleton births between 1986 and 1996. Main Outcome Measures Risks and relative risks for stillbirth (>20 weeks), preterm delivery (<37 weeks), and fetal growth restriction (birth weight below 10th percentile for gestational age) in relation to abruption. Results The incidence of abruption was 1% (n = 530), Abruption was associated with an 8.9-fold (95% confidence interval [CI], 6.0-13.0) adjusted relative risk (aRR) of stillbirth. Preterm birth proportions among women with and without abruption were 39.6% and 9.1%, respectively, yielding an aRR of 3.9 (95% CI, 3.5-4.4). In the abruption group, 14.3% of neonates were growth restricted, compared with 8.1% among all other births (aRR, 2.0; 95% CI, 1.5-2.4). Extent of placental separation had a profound effect on stillbirth (aRR for 75% separation, 31.5; 95% CI, 17.0-58.4), although evident only among those with at least 50% separation. However, the risk of preterm delivery was substantially increased even for mild abruptions (aRR for 25% separation, 5.5; 95% CI, 4.2-7.3). Conclusions In this cohort, placental abruption had a profound impact on stillbirth, preterm delivery, and fetal growth restriction. The risk of stillbirth was dramatically increased for severe placental separation, but preterm delivery was common even among women with lesser degrees of placental separation.