The effect of smoking on serum human placental lactogen levels.

Serial serum samples (162) were drawn weekly from normal pregnant women (53) during the last month of gestation and measurements were made of the human placental lactogen (HPL) content. The women were interviewed as to their smoking habits and divided into nonsmokers (32) and smokers of from one to two packages of cigarettes per day (21). The infant birth weight and placental weights were not significantly different. The HPL levels were elevated in the women who smoked and the differences were significant at the thirty-sixth and thirty-eighth weeks. The importance of this in interpreting HPL as a placental function test and in terms of the biology of placental function and the control of protein hormone synthesis is emphasized.