Amniotic fluid lecithin/sphingomyelin ratio: comparison between an African and North American community.

One hundred nineteen samples of amniotic fluid obtained from healthy pregnant Nigerian women were analyzed for their lecithin/sphingomyelin (L/S) ratio. There was a gradual increase in the L/S ratio with increasing maturity from week 23 to week 42 when values of 0.69 and 5.73, respectively, were obtained. Compared with the ratios reported from San Diego, our ratios were significantly higher where numbers were adequate for statistical tests. The higher L/S ratio probably shows that pulmonary maturity occurs earlier in the African babies and might partly explain the low incidence of respiratory distress syndrome in our premature babies.