Serum unconjugated estriol level as a predictor of pulmonary maturity

Lack of respiratory distress syndrome in infants delivered after the maternal serum estriol value attained greater than or equal to 15 ng/ml was investigated. In 91 cases after 34 weeks' gestation no lecithin-sphingomyelin ratio less than 2.0 was found where the serum estriol level was greater than or equal to 15 ng/ml and no respiratory distress syndrome in the patients delivered less than or equal to 3 days from amniocentesis.