Basal lamina thickening in the placentae of smoking mothers.

The thickness of the basal lamina in the placentae of 20 matched pairs of smoking and non-smoking mothers was measured using an electron microscopic method of quantification. A significant increase of the thickness of the trophoblastic basal lamina was found in the smokers' placentae: 181 nm (s.d. +/- 38.2 nm) in non-smokers versus 286 nm (s.d. +/- 69.9 nm) in smokers (P less than 0.005). A significant increase of the thickness of the capillary basal lamina was also found: 75 nm (s.d. +/- 12.1 nm) in non-smokers versus 111 nm (s.d. +/- 16.0 nm) in smokers (P less than 0.005). The number of duplications around the capillary basal lamina was found to be increased in the placentae of smoking women.