Racial and environmental influences on fetal lung maturation.

Claims that fetal lung maturation is more rapid in blacks than in whites were investigated. Histologic measurements of lung maturation and the frequency of hyaline membrane disease were compared in four groups of Neonates: 490 South African blacks, 841 Ethiopians, 767 US blacks, and 560 US whites. Lungs matured much more rapidly in the Ethiopian and more slowly in the South African than in the US fetuses. The rate of maturation was about the same in the US blacks and whites. Hyaline membrane disease was more frequent in the South Africans and less frequent in the Ethiopians than in either US group. Environmental factors in the mother may explain some of these differences. Lungs matured more rapidly in the fetuses of cigarette smokers than in fetuses of nonsmokers. Half of the US mothers but almost none of the South African mothers smoked during pregnancy. The rate of lung maturation had an inverse correlation with maternal body weights. The South African women were heavier and the Ethiopians lighter than women in the United States.