Main findings
To the best of our knowledge, this is the first study to elucidate the
risk factors for placental abruption based on the data of a large cohort
study conducted in Japan. Consistent with several studies, the present
study demonstrated that history of placental abruption, ART pregnancy,
smoking during pregnancy, chronic hypertension, and maternal age were
the risk factors for placental abruption. We also found that compared to
advanced maternal age, teenage maternal age was more strongly associated
with placental abruption. The number of previous deliveries was not
associated with the incidence of placental abruption.