RÉSUMÉ
【Objective】 To explore the factors influencing newborn birth weight under the universal two-child policy in Xi’an so as to provide information for maternal health. 【Methods】 For this study we selected the mothers who delivered babies at Xi’an Northwest Women’s and Children’s Hospital from May 2018 to November 2019. Their data included maternal demographic characteristics， delivery mode， and infants’ outcomes. Single factor analysis and multi-factor linear regression methods were used to analyze the factors influencing the birth weight of newborns of different age and mothers’ parity after the universal two-child policy. 【Results】 The newborns’ average birth weight was （3 377±449） g. The incidence of low birth weight and macrosomia was 7.4% and 2.5%， respectively. Multivariate linear regression analysis showed that gestational week of delivery （β=0.322， P0.05）. 【Conclusion】 Maternal women should do a good job in pre-pregnancy assessment， control pre-pregnancy weight， and gain reasonable weight during pregnancy. The community and hospitals should strengthen pre-pregnancy health education so as to scientifically and effectively improve maternal and infant outcomes.