In 126 pregnant women of the gestational age from the 28th to the 44th gestational week, the biparietal diameter, the abdomen diameter, and the placental maturity after Granum et al. were determined. Amniocentesis was performed for obstetric indication. Also the L/S ratio and the cytological estimation of the gestational age were recorded. The first degree of the placental maturity was found in 37, the second degree in 3, and the third degree in 36 pregnant women. In the first group, BPP was 8.38 +/- 0.75, the abdomen diameter 8.30 +/- 0.63, and pulmonary maturity in 73% of women according to the L/S ratio and in 91.9% according to cytological estimation. In the second group, BPP was 9.15 +/- 0.65, the abdomen diameter 9.03 +/- 0.83, and in 77.9% of women the L/S ratio was higher than 2 but in 56.6% of women, according to cytological estimation, there was a good pulmonary maturity. At the third degree of placental maturity, BPP was 9.49 +/- 0.60, the abdomen diameter 9.63 +/- 0.92, and a good pulmonary maturity in 94.4% of women. The RDS was not observed in 5.6% of newborns with the L/S ratio below 2. According to cytological estimation, BPP below 9.15 was found in pre-term labour and higher than 9.15 in at-term births when in 94% of women the L/S ratio was higher than 2.