Intra- versus retroplacental hematomas: a retrospective case-control study on pregnancy outcomes

Intrauterine hematomas are a common pregnancy complication. The literature lacks studies about outcomes based on hematoma localization. Thus, we aimed to compare pregnancies complicated by an intraplacental hematoma to cases with a retroplacental hematoma and to a control group. In a retrospective case-control study, 32 women with an intraplacental hematoma, 199 women with a retroplacental hematoma, and a control group consisting of 113 age-matched women with no signs of placental abnormalities were included. Main outcome measures were pregnancy complications. Second-trimester miscarriage was most common in the intraplacental hematoma group (9.4%), followed by women with a retroplacental hematoma (4.2%), and controls (0%; p = 0.007). The intraplacental hematoma group revealed the highest rates for placental insufficiency, intrauterine growth retardation, premature preterm rupture of membranes, preterm labor, preterm delivery <37 weeks, and early preterm delivery <34 weeks (p < 0.05), followed by the retroplacental hematoma group. When tested in multivariate models, intraplacental hematomas were independent predictors for placental insufficiency (s = 4.19, p < 0.001) and intrauterine growth restriction (s = 1.44, p = 0.035). Intrauterine fetal deaths occurred only in women with a retroplacental hematoma (p = 0.042). Intra- and retroplacental hematomas have different risk profiles for the affected pregnancy and act as independent risk factors.