Association of maternal serum α-fetoprotein with persistent placenta previa

Objective: To evaluate the relationship between maternal serum α-fetoprotein (MSAFP) and the risk of persistent placenta previa. Methods: We conducted a retrospective cohort study of singleton pregnancies with sonographic evidence of placenta previa at 15-20 weeks' gestation, between October 1991 and August 2000. Only pregnancies with MSAFP determination at 15-20 weeks' gestation and non-anomalous live-born infants ≥ 24 weeks' gestation were included. Pregnancies in which Cesarean delivery was performed for placenta previa were considered persistent; this was the primary outcome. Results: Of 275 women with previa at 15-20 weeks' gestation, 33 (12%) had previa at delivery. Trend analysis revealed a greater likelihood of persistent previa with increasing MSAFP values (p = 0.01). Mid-trimester MSAFP < 1 multiple of the median (MoM) was associated with a decreased incidence of persistence of 4%, significantly less than the risk at ≥ 1 MoM (16%; p = 0.01). Conclusions: There is an association between increasing MSAFP values and greater likelihood of persistent placenta previa. An MSAFP value < 1 MoM is associated with a reduction in the risk of persistence of previa to delivery.