关键词: 婴儿, 出生时低体重；流行病学监测；流行病学因素；影响因素分析；河北

Abstract: Background　Low birth weight infants often have chronic intrauterine hypoxia，their perinatal mortality rate is high，and the long-term physical development is backward and the risk of neurodevelopmental abnormalities is also high. Objective　To analyze the epidemiological characteristics of low birth weight infants and related factors affecting low birth weight infants in Hebei Province. Methods　The maternal and child monitoring information management system of Hebei Province was used to collect data of pregnant women at 37 weeks and above from 22 monitoring sites including 7 provincial and municipal hospitals and 15 county-level hospitals in Hebei Province from 2013 to 2017. Survey indicators included maternal age，birth year，birth season，urban-rural and rural grade distribution of birth hospitals，number of birth checkups，pregnancy times，parity times，fetal gender，the combination with gestational hypertension，gestational diabetes，heart disease and kidney disease，placental abruption，placenta previa，prolonged pregnancy and other related factors. Multivariate Logistic regression was used to analyze the influencing factors of low birth weight infants. Results　Among 250 304 full-term newborns，3 482 cases were low birth weight，with an incidence of 1.39%. There were statistically significant differences in the incidence of low birth weight infants among pregnant women of different ages，birth years，birth seasons，birth regions，urban-rural and rural grade distribution of birth hospitals（P<0.05）. The incidence of low birth weight was the highest（1.65%）among pregnant women with childbearing aged ≥40 years，and the lowest（1.29%）among women aged 30 to 34. The incidence of low birth weight infants was highest in 2015（1.56%）and lowest in 2017（1.29%）. The incidence of low birth weight infants was highest in spring（1.47%）and lowest in autumn（1.29%）. The city of Cangzhou had the highest incidence of low birth weight（1.82%），while Xingtai had the lowest incidence（0.82%）.The incidence of low birth weight infants in provincial and municipal hospitals（1.71%）was higher than that in township hospitals（1.13%）. The incidence of low birth weight infants was highest in tertiary hospitals（1.94%）and lowest in primary hospitals（0.98%）. There were statistically significant differences in age distribution，number of antenatal examinations，the number of pregnancy and parity，fetal sex，proportion of gestational hypertension，proportion of heart disease，proportion of kidney disease，proportion of placental abruption，proportion of placenta previa and proportion of prolonged pregnancy between the low birth weight group and non-low birth weight group（P<0.01）. There was no significant difference in education level and proportion of gestational diabetes mellitus（P>0.05）. Multivariate Logistic regression analysis showed that lower education level of pregnant women，fewer times of birth check-up，female fetus，delivery in provincial and municipal hospitals，gestational hypertension，heart disease，placental abruption，placenta previa were independent risk factors for low birth weight（P<0.05）. Multiple pregnancies，gestational diabetes mellitus and prolonged pregnancy were independent protective factors for low birth weight infants（P<0.05）. Conclusion　The incidence of low birth weight infants varies significantly in time，region and population. Individualized preventive measures should be taken for different regions and populations，such as timely pregnancy and standardized prenatal examination，early detection of potential high-risk factors，timely prevention and treatment to reduce the incidence of low birth weight infants.

Key words: Infant, low birth weight；Epidemiological monitoring；Epidemiologic factors；Root cause analysis；Hebei