Abstract: 　Objective　To investigate factors affecting neonate birth weight. Methods Random cluster sampling method was adopted to investigate the physical development of 5539 single live newborns in Beijing, Harbin, Changsha, and Guangzhou. Single factor analysis and logistic regression analysis were used to find the factors influencing neonate birth weight. Results Single factor analysis showed that neonatal sex, gestational age, maternal age, maternal pre-pregnancy BMI, gestational weight gain, mother's education and occupation have effects on neonatal birth weight. Risk factors for macrosomia, including male fetus, maternal age ≥ 25 years before pregnancy, maternal pre-pregnancy BMI ≥ 24 kg/m2, gestational weight gain greater than 12.5 kg, and preterm delivery and maternal pre-pregnant BMI < 18.5kg/m2 are the risk factors of low birth weight. Conclusions Premature, excessive weight gain during pregnancy, high or low maternal pre-pregnancy BMI are main factors that caused abnormal body mass in neonates.