Pregnancy outcome in North American women. II. Effects of diet, cigarette smoking, stress, and weight gain on placentas, and on neonatal physical and behavioral characteristics.

This study evaulated the effects of diet, weight gain (low = LWG, less than or equal to 15 lb; adequate greater than 15 lb), smoking, and stress on the pregnancy outcomes of 60 women. LWG mothers, compared to adequate weight gain, had lower calorie intakes, shorter gestations (0.5 wk, Dubowitz) smaller placentas (345 +/- 65 versus 373 +/- 75 g), and infants with lower birth weight 2640 +/- 329 versus 3192 +/- 307 g), ponderal indices (2.37 versus 2.62), and growth rates. Mothers who smoked had increased calorie intake, but showed no alterations in gestational age of infants or placenta weights. Infants of smokers weighed less than those of nonsmokers (2875 +/- 522 versus 309 +/- 511 g), but had a normal ponderal index. LWG or smoking were associated with impaired motor performance, visual habituation and orientation, and reflexes. Smoking adversely affected auditory habituation and orientation, and autonomic regulation. LWG and smoking have significant, but separate, detrimental effects on pregnancy outcome.