[Amniotic AFP concentration in pregnancies with numerical chromosome aberrations].

Amniotic fluid alpha-fetoprotein concentration were measured in 360 normal pregnancies between 15 and 23 weeks gestation. Taking into account the effect of gestational age the mean and SD were calculated, confirming the physiological decrease in AFP levels at the beginning of the second trimester. By comparison 25 pregnancies with trisomic states (23 trisomy 21, 2 trisomy 18) showed AFP levels below the control mean in 19 cases. In 5 cases we found AFP concentrations above the control mean, partly even not included in the range of 1 SD and in one case the AFP concentration was at the control mean. These results lend further support to the observation of lower amniotic fluid AFP levels in pregnancies with numerical chromosomal aberrations. In all but 6 cases AFP levels ranged not more than 1 SD below the control mean. No clinical consequences can therefore be based on these data.