Maternal Serum Alpha-Fetoprotein as a Predictor of Persistent Low-Lying Placenta and Placenta Accreta Spectrum: A Prospective Observational Study

Introduction Placenta previa and low-lying placenta are major contributors to antepartum hemorrhage and are strongly associated with placenta accreta spectrum, a leading cause of severe maternal morbidity. Early identification of pregnancies at risk remains clinically important. Maternal serum alpha-fetoprotein (MS-AFP), routinely measured during antenatal screening, has been proposed as a biomarker of abnormal placentation. This study evaluated the association between maternal serum alpha-fetoprotein levels and persistence of low-lying placenta, as well as its predictive value for placenta accreta spectrum. Methods This observational study was conducted in the Department of Obstetrics and Gynaecology, Patna Medical College and Hospital, Patna, Bihar, India. Sampling was performed using a convenience sampling approach. Consecutive eligible pregnant women attending the Department of Obstetrics and Gynaecology between November 2019 and October 2021 who fulfilled the inclusion criteria were recruited until a total of 100 participants was achieved. One hundred pregnant women with ultrasonographically confirmed low-lying placenta between 15 and 20 weeks' gestation were enrolled. Maternal serum alpha-fetoprotein levels were measured and expressed as multiples of the median. Participants were followed until delivery to assess placental migration, occurrence of placenta accreta spectrum, and obstetric outcomes. Statistical analysis was performed using appropriate comparative tests, with statistical significance defined as a p-value less than 0.05. Results Among the 100 enrolled women, low-lying placenta persisted in 45 (45.0%), whereas placental migration occurred in 55 (55.0%). Subsequent analyses demonstrated that persistence was significantly associated with prior cesarean delivery and multiparity. Placenta accreta spectrum occurred in 13 (13.0%) women, all of whom had persistent low-lying placenta. Elevated maternal serum alpha-fetoprotein levels were present in 88.9% of persistent cases and in all cases of placenta accreta spectrum. MS-AFP values greater than 1.1 MoM were associated with persistence, while MS-AFP values exceeding 1.7 MoM (multiples of the median) were strongly related with the need for cesarean hysterectomy. Conclusion MS-AFP may serve as a useful adjunctive marker for identifying pregnancies at an increased risk of persistent low-lying placenta and placenta accreta spectrum. Larger prospective studies are needed to validate these findings. These findings suggest that MS-AFP may complement ultrasonographic assessment; however, further prospective studies are required to evaluate its additional diagnostic value.