Alpha fetoprotein: Physiology and pathology during pregnancy and application to antenatal diagnosis.

Alpha fetoprotein (AFP) is synthesized by the x human fetal liver and yolk sac [8, 9]. During the 12—14 intrauterine weeks the serum concentration of AFP is at its highest, reaching a few milligrams per ml [7]. However, the total amount of AFP in the fetus increases until the 22 week of gestation, remaining constant until about the 32 week, and thereafter decreasing [7]. In the newborn at term, the serum AFP concentration is 50—ISO^g per ml [19]. AFP remains detectable by immunodiffusion or related methods for about 5 weeks after birth [24]. Greatly increased serum AFP levels cften reappear in adults with primary hepatocellular cancer [25] or teratocarcinomas [1]. Until recently, the occurrence of AFP in maternal serum had been contested [3]. We purified immunochemically human AFP [14] and developed a radioimmunoassay (RIA) for its determination [15]. It became evident thät small amounts (2—16 ng per ml) of AFP are present in normal human serum [15, 16]. This finding has now been confirmed by other groups [6, 13]. AFP levels in maternal serum increase during pregnancy and the highest AFP concentrations occur during the third trimester. The half life of maternal serum AFP after delivery is about 5 days [19]. In amniotic fluid, the AFP concentrations decrease from the 15 week of gestation, and at term the concentrations are similar to those in maternal serum [19, 21]. Recently, we found that the maternal serum AFP concentration often increases in assoCurriculum vitae