Evaluating health and maturation of the unborn: the role of the clinical laboratory.

I review the utility of several common prenatal laboratory tests. Infant mortality is higher in the United States than in many other industrialized nations; better access to early prenatal care may help reduce this mortality rate. Several common laboratory tests can significantly contribute to prenatal care. Early measurement of maternal serum human chorionic gonadotropin can permit estimation of the date of conception. Use of maternal serum alpha-fetoprotein in the second trimester provides the clinician with risk estimates for neural tube defects and Down syndrome. Adding human chorionic gonadotropin and possibly unconjugated estriol to this screen can increase the number of Down syndrome cases identified without increasing the proportion of abnormal results. Amniotic fluid fetal lung maturity tests can assist with the management of delivery.