Placental Abruption in Term and Preterm Gestations

OBJECTIVE: To estimate the magnitude of associations of acute and chronic processes with abruption in preterm and term gestations. METHODS: A retrospective cohort study was performed using data on women that delivered singleton live births and stillbirths at 20 or more weeks of gestation in the United States, 1995-2002 (n = 30,378,902). Rates of 1) acute-inflammation-associated clinical conditions (premature rupture of membranes and intrauterine infection); 2) chronic processes associated with vascular dysfunction or chronic inflammation (chronic and pregnancy-induced hypertension, preexisting or gestational diabetes, small for gestational age, and maternal smoking); and 3) both acute and chronic processes, were examined among women with and without abruption. Rates were examined separately among preterm (< 37 weeks) and term births, with adjustment for confounders. Relative risk (RR) for aforementioned groups in relation to abruption was derived from multivariate logistic regression models after adjusting for potential confounders. RESULTS: At preterm gestation, the rates of acute-inflammation-associated conditions were higher among women with than without abruption (12.0% compared with 10.2%; RR 1.38, 95% confidence interval CI 1.34-1.42). At term, acute-inflammation-associated conditions were present in 4.2% and 3.3% of births with and without abruption, respectively (RR 1.39, 95% CI 1.33-1.45). At preterm gestation, the rates of chronic processes were 43.9% and 30.0% among women with and without abruption, respectively (RR 1.87, 95% CI 1.85-1.90). At term, the corresponding rates of chronic processes were 41.0% and 22.7%, respectively (RR 2.37, 95% CI 2.34-2.41). Association between both acute and chronic processes and abruption are similar to those of acute-inflammation-associated conditions. CONCLUSION: Among women with placental abruption, conditions associated with acute inflammation are more prevalent at preterm than term gestations, whereas chronic processes are present throughout gestation. LEVEL OF EVIDENCE: II-2.