Nutrient intakes during pregnancy: observations on the influence of smoking and social class.

The influence of smoking and social class on dietary intake in pregnancy was investigated in a random sample of smokers (greater than or equal to 15 cigarettes/d) and nonsmokers. A total of 206 subjects (94 smokers and 112 nonsmokers) completed a 7-d weighed dietary intake at 28 wk gestation and 178 completed a second assessment at 36 wk. Nonsmokers had higher intakes of almost all nutrients than did smokers and the nutrient density of their diet was greater. Energy intake was nonsignificantly higher in nonsmokers. Women in higher social classes had the highest nutrient intakes. Smokers were shorter than nonsmokers and tended to be of lower social class. After maternal height and social class were controlled for, smoking had a significant effect on intake of many micronutrients. Dietary intake was reduced in late pregnancy, particularly in smokers. These data suggest that smokers in all social classes have a poorer quality of diet.