Abstract: Objective To explore the effect of pre-pregnancy weight and weight gain of primiparas during pregnancy on neonatal weight. Methods Healthy primiparous pregnant women and their single live births without obstetric complications were recruited from a hospital in Harbin in 2018. Records of parturient examination and delivery were collected, a questionnaire survey on the parturients was conducted, and the parturient women were divided into groups based on the Chinese standard BMI for adults. Factors affecting the weight of newborn and effects of pre-pregnancy weight and weight gain during pregnancy on neonatal weight were analyzed. Result sIn this study, 826 healthy primiparas and their newborns were investigated. The average age of primiparas was (26.36 ± 4.21) years, the average BMI before pregnancy was (22.18 ± 3.15). Of the primiparas, 46.12% had the education level of college or above and 83.41% lived in the cities or towns. The average weight gain during pregnancy was (15.26 ± 4.12) kg, and the average gestational week was (38.83 ± 1.08) weeks. Of the 826 newborns, the male to female sex ratio was 1.15∶1,17 (2.1%) low birth weight, 748 (90.6%) normal birth weight, and 61 (7.4%) macrosomia. There were statistically significant differences in family income per month, pre-pregnancy BMI, and weight gain during pregnancy among pregnant women who gave birth to newborns (all P <0.01). There were statistically significant differences in the distribution of body weight of newborns with different weights before pregnancy and different weights during pregnancy (all P <0.01). Both the weight before pregnancy and the weight during pregnancy were positively correlated with the birth weight of the newborns (r =0.147, 0.239). Conclusion Pre-pregnancy weight and weight gain during pregnancy affected the birth weight of newborn, pre-pregnancy obesity and excessive weight gain during pregnancy were likely to increase the risk for macrosomic infant birth. Therefore, prenatal health education for primiparas should be strengthened.

Key words: Primipara, Body weight, Weight gain during pregnancy, Newborn