Association of maternal serum alpha-fetoprotein with persistent placenta previa.

OBJECTIVE

To evaluate the relationship between maternal serum alpha-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 > or =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 > or =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.