Analysis on the birth situation different fertility policy periods in monitoring area of birth defect population in Zhejiang Province

Abstract

Objective: To explore the impacts on birth situation associated with birth policy adaption in monitoring area of birth defect population in Zhejiang province. Methods: Data were obtained from hospital-based birth defect surveillance system in Zhejiang Province. The surveillance population was childbearing women living in Nanhu of Jiaxing and Fenghua of Ningbo no less than 1 year. We divided data into three groups as "only child" (Jan, 2012-Sep, 2013), "privileged second child" (Jan, 2015-Sep, 2016) and "universal second child" (Jan, 2017-Sep, 2018) according to birth policy adaption. The differences of maternal age distribution in different birth policy periods were compared by using Kruskal-Wallis test. The changing trend of the proportion of parturient in different birth policy periods was analyzed by using Trend χ(2) test. Unconditional logistic regression model was used to analyze the relationship between birth policy and adverse perinatal outcomes. Results: During "only child" , " privileged second child" and "universal second child" period, the number of childbearing women was 12 557, 14 097 and 15 509, respectively, with an increase of 12.3% and 10.0% over previous periods. Maternal ages [M (P(25), P(75))] were [27 (25, 30)], [28 (26, 31)] and [28 (26, 32)] years old. The proportion of multipara in each period was 19.5%, 35.7% and 45.8%, showing an increased trend (P<0.001). The incidence of adverse perinatal outcomes was lowest in the "only child" period (8.7%) and highest in the "universal second child" period (11.1%). Unconditional logistic regression model showed that after adjusting for age, compared with the "only child" period, the risk of premature birth [OR values (95%CI) were 1.20(1.08-1.33) and 1.08 (1.02-1.13), respectively] and birth defects [OR values (95%CI) were 1.33(1.13-1.55) and 1.29 (1.20-1.39), respectively] increased in "privileged second child" and "universal second child" period. The risk of macro infants decreased significantly [OR values(95%CI) were 0.87 (0.80-0.96) and 0.91 (0.87-0.95), respectively], and the risk of perinatal death changed insignificantly [OR values (95%CI) were 0.78 (0.53-1.15) and 0.84 (0.69-1.02), respectively]. Conclusion: According to population based surveillance in two regions in Zhejiang, the proportion of women with advanced age, the proportion of multipara , the risks of birth defects increased with birth policy adaption.