[Comparative evaluation of methods for predicting fetal lung maturity based on serial amniotic fluid tests (author's...

12 pregnant females in the last trimester were subjected to serial amniocentesis. Although there was medical indication for amniocentesis the pregnancies were normal. All samples were evaluated with four different methods. We used two physical (Wilhelmy balance and foam test) and two chemical (L/S ratio densitometrically and planimetrically measured) methods. The Curves of individual pregnancies were compared with the reference values of 109 samples of amniotic liquid of uncomplicated pregnancies. Reference values for the various techniques reported in the literature are generally based on aggregate data collected from a number of pregnant females, which are then consolidated to obtain mean values for each gestational week. We found a continuous rise of all parameters, both in the reference value and in eight individual pregnancies. Besides we found a strikingly extraordinary run of the curves in four individual pregnancies. Here we recognized a rapid ascent and descent of surfactant concentration within short periods, which were not identical with the reference values. All four methods showed results with a statistical significant conformity, only the foam test showed a little lower significance.