Ossification centers as evidence of fetal lung maturity.

Fetal pulmonary maturity based on visualization of one or both fetal knee secondary centers of ossification was assessed in 84 gravidas. Amniotic fluid lecithin/sphingomyelin ration of 2:1 or greater was the criterion of fetal lung maturity. It was concluded that when antenatal radiographs reveal the presence of both centers of ossification, fetal lung maturity can be assured in 100% of the fetuses. When the distal femoral center along is seen, only 60% of the fetuses will have mature lungs.