[The estimation of surface actitity of the lungs in dependence from duration of pregnancy (author's transl)].

The surface tension of amniotic fluid was measured in a Langmuir balance in 98 persons with normal pregnancy between 23 and 42 weeks of gestation. An increase of surface activity in dependence of gestational ages was found. It is possible to use the surface tension of amniotic fluid as an indicator of fetal pulmonary maturity in high risk pregnancy.