[Preliminary investigations of the serum alpha-1-fetoprotein level in mature and premature newborn infants (author's transl)].

Semiquantitative determination of the serum AFP concentration was carried out in 170 newborn infants (mature and premature) by means of crossover electrophoresis on admission to hospital and at 1 to 2 weekly intervals thereafter. The infants were divided into 3 groups according to their birth weight and also grouped according to gestational age into 3 further groups. The serum AFP level was correlated with the age in weeks of the infants for each group separately. Mature newborn infants with a birth weight of over 2500 g show a rapid fall in serum AFP titre; AFP is no longer detectable after the 9th week of life. In premature infants with a birth weight of 1500 to 2500 g, the fall in AFP titre is delayed and reaches zero between the 7th and 13th week of age. There is a markedly slower decrease in serum AFP concentration in the group of immature infants with a birth weight of under 1500 g; the limit of detectability lies between the 13th and the 17th week of age. An almost identical pattern is revealed when the infants are grouped according to gestational age. The possibility of diagnosing the small for date babies and severe liver disease by means of the serum AFP titre is discussed.