Gestational-Age Clustering of Recurrent Placental Abruption: A Multicenter Retrospective Descriptive Study

Background/Objectives: Placental abruption has a high risk of recurrence, but the timing of recurrence relative to the previous episode remains unclear. This study described the gestational-age distribution of recurrent placental abruption and compared recurrent with first-time placental abruption in multiparous women. Methods: This retrospective multicenter descriptive study included 239 hospital-managed cases of placental abruption at nine perinatal centers in northern Japan from 2003 to 2024. Clinical characteristics and outcomes were compared between multiparous women with recurrent placental abruption (n = 10) and those with first-time placental abruption and no prior history of placental abruption (n = 134). Recurrence timing was assessed descriptively by comparing gestational age at onset between previous and current episodes. Results: Among 239 cases, 10 women had recurrent placental abruption. Maternal age was higher in the recurrent group, whereas BMI, smoking, assisted reproductive technology, and hypertensive disorders of pregnancy were similar between groups. Most clinical features and maternal and neonatal outcomes did not differ significantly, although birth weight was higher in the recurrent group. Among 11 recurrent events, 6 occurred within ±1 week (54.5%; exact 95% CI, 23.4-83.3%) and 8 within ±2 weeks (72.7%; exact 95% CI, 39.0-94.0%) of the previous gestational age. Available placental pathology in recurrent cases was reviewed descriptively only and was not interpreted as evidence of an association between maternal vascular malperfusion and recurrence. Conclusions: In this small exploratory cohort, recurrent placental abruption tended to occur within approximately ±1 to ±2 weeks of the gestational age of the previous episode, with 6 of 11 recurrent events occurring within ±1 week and 8 of 11 occurring within ±2 weeks. These exploratory findings may assist clinicians when individualizing surveillance strategies but should not be interpreted as supporting a specific surveillance protocol; confirmation in larger datasets is required.