Abstract: Objective To analyze the change trend and influencing factors of the incidence of very low and low birth weight infants in Xi'an, and to provide theoretical basis for the prevention and treatment of very low and low birth weight infants. Methods Data of infants registered in Xi'an and born in Northwest Women's and Children's Hospital and their mothers from 2014 to 2019 were collected from the maternal and infant management system in the region. The incidence of very low and low birth weight infants was retrospectively analyzed, and the influencing factors of very low and low birth weight infants were analyzed. Results From 2014 to 2019, 41 683 newborns were born live in Xi'an, of which 387 were born with very low birth weight, accounting for 0.93%, with an average birth weight of （1 190.8±232.1） g. There were 1 182 low birth weight infants, accounting for 2.84%, with an average birth weight of （2 195.4±240.1） g. The incidence of very low birth weight and low birth weight was significantly decreased from 2014 to 2019 （P<0.01）. Multivariate Logistic regression analysis showed that pre-pregnancy body mass index ≤ 18.5 kg/m² （OR=4.104）, placenta abruption （OR=2.732）, placenta previa （OR=3.093）, premature rupture of membranes （OR=3.557）, complicated with gestational hypertension （OR=2.519）, multiparous （OR=4.586）, multiple births （OR=3.056）, and premature delivery （OR=3.823） were the risk factors for very low and low birth weight infants. Conclusions The incidence of very low and low birth weight infants in Xi'an is decreasing year by year, but the current situation is not optimistic due to the influence of many factors. Comprehensive preventive measures should be taken for pregnant women with risk factors to reduce the incidence of very low and low birth weight infants.

Key words: Newborn, Very low birth weight infant, Low birth weight infant, Change trend, Influence factor