Abstract: Objective To analyze the occurrence and related factors of adverse delivery outcomes of second-born pregnant women in Kaifeng City, and provide a basis for formulating intervention measures to avoid adverse maternal and infant outcomes.Methods A second-born pregnant woman who had established a fertility file and gave birth in the obstetrics department of a hospital in Kaifeng from January 2017 to December 2019 was selected as the research object. The basic conditions and complications of pregnancy were collected, and the relevant data of delivery were matched. Descriptive epidemiological analysis was used to analyze, and univariate and multivariate analysis were used to analyze the factors affecting the adverse delivery outcomes.Results A total of 2 208 second-born pregnant women who met the research conditions and matched the obstetric data were included in the study, aged 23-43 years old, with an average age of （30.93 ± 5.71） years. The pre-pregnancy BMI of 18.5~23.9 kg/m² accounted for 66.17%. Secondary specialized school or high school was the main educational level （39.67%）. The annual household income was mainly 50,000 to 90,000 yuan （50.68%）. 1 689 had a normal delivery outcome, and 519 had an adverse delivery outcome, with an incidence rate of 23.51%. Among them,21 cases were stillbirths （4.05%）, 183 cases （35.26%） were born prematurely, 81 cases （15.61%） were giant infants, 87 cases （16.76%） were low birth weight infants, 57 cases （10.98%） were neonatal asphyxia,66 cases （12.72%） were neonatal respiratory distress syndrome, and 24 cases （4.62%） were neonatal deformity. Multivariate logistic regression analysis showed that ages were 35-38, 39-43 years （OR=5.083, 10.433）, pre-pregnancy BMI≥24.0 （OR=3.375）, abortion frequency ≥ 3 tines（OR=3.725）, gestational hypertension （ OR=2.452）, gestational diabetes （OR=4.191）, fetal distress （OR=2.040）, and premature rupture of membranes （OR=7.338） were risk factors for adverse delivery outcomes in second-born pregnant women.Conclusion The incidence of adverse delivery outcomes among second-born pregnant women in Kaifeng is relatively high, and premature delivery is the main adverse outcome. There are many factors influencing adverse delivery outcomes. It is recommended to strengthen health education for second-born mothers during pregnancy, develop adaptive birth plans for advanced age parturient women and second-born pregnant women with complications, screen for high-risk pregnancy factors and clinical intervention management, reduce adverse pregnancy and delivery outcomes, and ensure maternal and infant safety.

Key words: Pregnant woman, Second pregnancy, Delivery outcome, Influencing factor