Maternal serum alpha-fetoprotein levels in low birth weight singleton pregnancies

Maternal serum alpha fetoprotein (MSAFP) measurement between 16 and 21 weeks gestation is used to define a group of women with an increased risk of fetal abnormality, particularly open neural tube defect. The test is strongly gestation dependent and women with high MSAFP levels require sonar scan examination to define gestation, exclude twins and examine the fetus for obvious malformation or death. It has been reported that women with no primary cause for raised MSAFP have an increased incidence of low birth weight babies. Conflicting reports have separately ascribed these to premature delivery and to intra-uterine growth retardation. We have studied the relationship between MSAFP and low birth weight infants with respect to both prematurity and retarded fetal growth. MSAFP values were expressed as multiples of the appropriate weekly median (MOM) values relating to normal pregnancies with normal outcomes at term. For our normal population an MSAFP value of 2 MOM is the 95% centile, i.e. 5% of normal outcome pregnancies of sure gestation will have MSAFP values in the second trimester which are at or above 2 MOM. Information was available on 389 women whose infants were liveborn singletons weighing 2.5 kg or less. 33 (8.5%) of these women had MSAFP greater than 2 MOM (p less than 0.005) and of the 145 women whose babies weighed less than 2 kg, 17 (11.7%) had MSAFP at this level (p less than 0.001) Tab. I).(ABSTRACT TRUNCATED AT 250 WORDS)