Pregnancy outcome in North American women. I. Effects of diet, cigarette smoking, and psychological stress on maternal weight gain.

This study examined the roles of diet, cigarette smoking, and psychological stress in pregnancy weight gain. The 60 were selected by defined criteria to minimize variation in anthropometric, socioeconomic, and medical variables which also affect weight gain. To maximize variation in weight gain, subjects were also selected on the basis of low weight gain (less than or equal to 15 lb) and adequate weight gain (greater than 15 lb). Each weight gain group contained smokers and nonsmokers. Smokers consumed more calories than nonsmokers (2119 versus 1810 kcal/day, p less than 0.01). for nonsmokers, differences between the intakes of low weight gain (1617 kcal/day) and adequate weight gain (1905 kcal/day) women were significant (p less than 0.02) and calorie intake was correlated with weight gain (r=0.44 p, less than 0.02). Psychological stress negatively correlated with weight gain (r=0.37, p less than 0.01) but not with calorie intake. We conclude that low weight gain is associated with a lower food intake. In contrast, smoking and stress may cause low weight gain by reducing the utilization of calories for weight gain.