The Effects of Parity on the Birth Weight in Fengtai District, Beijing from 2015 to 2017

Abstract

Abstract Objectives The aim of the current study was to explore the effects of parity on the birth weight in Fengtai district, Beijing, around the two-child policy complete implementation in China. Methods This is a retrospective study, with 57,987 live, singleton birth selected from Fengtai district, Beijing from 2015 to 2017. Data were divided into primiparous (n = 39,737) and secundiparous (n = 18,250), both maternal factors and neonatal outcomes were analyzed. ANOVA and Chi-square analysis were used to compare the difference within and between groups, and multiple linear regression models were used to assess the effects of parity on the birth weight, adjusting for potential confounders. Results Comparing 2017 to 2015, the number of primiparous and secundiparous was increased by 43.4% and 155.3%, respectively. The average birth weight was heavier in secundiparous than primiparous (3391.95 ± 463.67 g vs 3344.66 ± 463.09 g, P < 0.001). Significant decrements in birth weight were observed in primiparous groups (18.40 ± 6.27 g, P < 0.05) and secundiparous (29.75 ± 9.79 g, P < 0.05) during the three years. No difference was found for the low birth weight ratio in primiparous (Chi-square = 1.549, P = 0.461) but was observed of a 0.7% increment in secundiparous (2.3% vs 3.0%, Chi-square = 7.741, P = 0.021) from 2015–2017. After multiple linear regression, significant positive correlations were observed between parity and birth weight and the β value was decreased in the three years (β2015 = 38.213; 95% CI: 22.518 to 53.908, P < 0.001; β2016 = 34.843; 95% CI:24.758 to 44.928, P < 0.001; β2017 = 25.137; 95% CI: 15.287 to 34.988, P < 0.001), adjusted by gender, birth length, maternal age, gestational week, number of abortion, mode of delivery, maternal education and maternal domicile. Conclusions The birth weight is higher among the secundiparous than the primiparous in Fengtai district Beijing during 2015–2017, and parity is an important factor affecting the birth weight. Funding Sources Nutrition Research Fund of Chinese Nutrition Society-Feihe Research Fund for Physical Nutrition and Health.