The relationship between perinatal outcome of singleton pregnancies and isolated highly elevated levels of maternal serum human chorionic gonadotropin at mid-gestation

Background: The measurement of maternal serum human chorionic gonadotropin as a predictor of fetuses with Down syndrome has been in use since 1987. Objectives: To determine the correlation between extremely high levels of hCG at mid-gestation and maternal and fetal complications. Methods: The study group consisted of 75 pregnant women with isolated high levels of hCG (> 4 MOM) at mid-gestation, and the control group comprised 75 randomly selected women with normal hCG levels (as well as normal alpha-fetoprotein and unconjugated estriol levels). In addition to demographic information, we collected data on fetal anomalies, chromosomal aberrations, pregnancy complications, and results of neonatal tests. Results: There was a significant increase in the frequency of fetal anomalies (detected by ultrasound), low birth weight and neonatal complications in the study group. We also found an increased rate of fetal/neonatal loss proportional to the increasing levels of hCG (up to 30% in levels exceeding 7 MOM). Conclusion: Our study demonstrated an increased frequency of obstetric complications that was closely associated with high hCG levels. The study also raises questions about the accuracy of the Down syndrome probability equation in the presence of extremely high levels of hCG where data on the frequency of Down syndrome are severely limited.