Familial Risk of Placental Abruption

Objective: This study aims to estimate the familial risk of placental abruption using a large population database. Design: Retrospective familial aggregation study of placental abruption utilizing a case-control design. Population: The Utah Population Database is a genealogic database of over 11 million individuals, which contains medical and demographic information linked to official records dating back to the 1900s. Methods: : Cases of placental abruption and controls were ascertained from birth certificates, death certificates, and inpatient medical records. Controls were matched 3:1 to cases based on age, parity, and number of relatives in the database. Familial risk of placental abruption was estimated using generalized linear mixed-effect regression and conditional logistic regression. Main outcome measures: Unadjusted and adjusted odds of placental abruption between first-, second-, and third-degree relatives. Results: : Of 1,168,378 pregnancies analyzed in the Utah Population Database, 32,823 cases (2.8%) of placental abruption were identified. First-degree relatives inherit an adjusted odds of placental abruption estimated at 1.18 (95% CI: 1.12 – 1.23) when a family member has had at least one placental abruption, and 1.38 (95% CI: 1.17 – 1.63) with two or more placental abruptions. The estimated effect is lower for second- and third-degree relatives. After controlling for clinical risk factors, individuals inherit an adjusted odds of placental abruption estimated at 1.16 (95% CI: 1.03 – 1.31, p =0.014) with a first-degree family history of placental abruption. The estimates for second- and third-degree relatives using this method are not statistically significant. Conclusion: These findings represent an argument for the inheritance of genetic factors which predispose the occurrence of placental abruption.