ABNORMAL LEVELS OF MATERNAL SERUM HUMAN CHORIONIC-GONADOTROPIN AND ALPHA-FETOPROTEIN IN THE 2ND-TRIMESTER - RELATION TO FETAL WEIGHT AND PRETERM DELIVERY

The aim of this prospective descriptive cross-sectional study was to e xamine the clinical significance of abnormal maternal serum human chor ionic gonadotropin (MShCG) and alpha-fetoprotein (MSAFP) in the second trimester of pregnancy. The study group comprised 8892 women with a s ingleton pregnancy, who were screened for a neural tube defect and Dow n's syndrome. Exclusion criteria were unknown pregnancy outcome, a con genital anomaly, delivery before 25 weeks of amenorrhoea, or known ins ulin-dependent diabetes. MSAFP and MShCG were determined between 15 an d 20 weeks' amenorrhoea. An abnormal result was defined as (a) MSAFP o r MShCG greater than or equal to 2.5 MOM, (b) MSAFP or MShCG less than or equal to 0.5 MOM, and (c) MSAFP and MShCG greater than or equal to 2.5 MOM. Birth weight percentiles and the duration of amenorrhoea at the time of delivery were employed as outcome parameters. Of the women with an abnormally elevated MSAFP, 9.4 per cent had an extremely smal l-for-gestational age (SGA) infant (<2.3rd percentile; P<0.01, relativ e risk 4.5), 27.1 per cent had an SGA infant (<tenth percentile; P<0.0 1, relative risk 2.7), and 14.3 per cent had an appropriate-for-gestat ional age (AGA) infant that was delivered preterm (<259 days; P<0.01, relative risk 2.4). In the cases where the MShCG level was elevated, 4 .4 per cent had an extremely SGA infant (P<0.01, relative risk 2.1) an d 15.5 per cent had an SGA infant (P<0.01, relative risk 1.5). No sign ificant association was found between an elevated MShCG level and pret erm delivery. Low MShCG was significantly associated with SGA infants (P<0.01, relative risk 1.2) but not with extremely SGA or preterm deli veries. In the group whose MSAFP and MShCG levels were both elevated, 23.8 per cent delivered an extremely SGA infant (P<0.01, relative risk 10.9), 38.1 per cent an SGA infant (P<0.01, relative risk 3.7) and 47 .6 per cent had a preterm delivery or an SGA infant (P<0.01, relative risk 3.0). Isolated or combined elevation of the MSAFP and MShCG level s in the second trimester of pregnancy is an indication for extra vigi lance during further prenatal care. This applies to a lesser extent to a low MShCG level.