Pregnancy outcome in women with low midtrimester maternal serum unconjugated estriol

OBJECTIVE: To determine if unexplained low second-trimester maternal serum unconjugated estriol (MSuE3) is a useful predictor of complications of pregnancy. STUDY DESIGN: Between February 1, 1990, and January 3, 1993, 10,492 patients underwent prenatal screening using second-trimester maternal serum α-fetoprotein (MSAFP), maternal serum human chorionic gonadotropin (MShCG) and MSuE3. One hundred ninety-five patients with complete obstetric history/delivery records and with <0.4 multiples of the median (MoM) second- trimester MSuE3 values were matched with 261 controls with complete obstetric history/delivery records and normal second-trimester MSAFP, MSuE3 and MShCG. RESULTS: The relative risk of pregnancy loss, as compared to that in controls, was 3.7 (1.4-9.1 confidence interval [CI], P < .0001) in patients with 0.2-0.4 MoM MSuE3 and 19.3 (6.1-60.5 CI, P < .0001) in patients with <0.2 MoM MSuE3. After exclusion of patients with low and high MSAFP and MShCG, the relative risk of pregnancy loss for the remaining patients with low MSuE3 was 3.3 (1.3-8.5 CI, P < .008). CONCLUSION: The data suggest that patients with unexplained low second-trimester MSuE3 have an increased risk of pregnancy loss that may not be associated with a high or low MSAFP, MShCG or higher incidence of pregnancy-induced hypertension, gestational diabetes, premature rupture of membranes or premature onset of labor.