Placenta Accreta Spectrum among Women with Twin Gestations

OBJECTIVE:To assess whether placenta accreta spectrum occurs more frequently among women with twin gestations compared with singleton gestations.METHODS:All live births in California from 2016 to 2017 were identified from previously linked records of birth certificates and birth hospitalization discharges. The primary outcome was placenta accreta spectrum (which includes placenta accreta, increta, and percreta), identified using International Classification of Diseases, Tenth Revision, Clinical Modification codes (O43.2x) for placenta accreta, increta, and percreta. We analyzed the association between twin gestation and placenta accreta spectrum by using multivariable logistic regression and assessed whether our findings were replicated by using a previously validated International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)-based approach.RESULTS:Among 918,452 live births, 1,126 were diagnosed with placenta accreta spectrum. The prevalence of placenta accreta spectrum was 11.8 per 10,000 among singleton pregnancies and 41.6 per 10,000 among twin pregnancies. In the unadjusted regression analysis, twin pregnancy was associated with higher relative risk of placenta accreta spectrum (RR 3.41, 95% CI 2.57-4.52). After adjusting the regression model for maternal age, previous cesarean birth, and sociodemographic factors, the association held with higher relative risk of placenta accreta spectrum (aRR 2.96, 95% CI 2.23-3.93). Women with twin compared with singleton gestations with placenta accreta spectrum were less likely to have placenta previa. When assessed using ICD-9-CM codes, placenta accreta spectrum was similarly more prevalent among twins than singletons, with an increase in the relative risk of placenta accreta spectrum (aRR 2.45, 95% CI 2.33-3.25).CONCLUSION:Twin gestation conferred an increased risk for placenta accreta spectrum independent of measured risk factors, which may contribute to increased maternal morbidity in twin gestation compared with singleton gestation. Clinicians should be aware of the increased risk for placenta accreta spectrum in twin gestation and should consider it during ultrasonographic screening.