May R. Prepregnancy weight, inappropriate gestational weight gain, and smoking: relationships to birthweight. Am J Hum Biol. May/Jun 2007;19(3):305-310.
The author tested predictors of infant birthweight, including prepregnancy body mass index, gestational weight gain, and smoking. Results showed that higher birthweight was predicted by prepregnancy obesity. Lower infant birthweight was predicted by both lower and higher-than-recommended weight gain and by lower and higher levels of smoking.