Epidemiological study on the influence of sex of the first-born child on the adverse birth outcomes of the second-born child / 西安交通大学学报(医学版)

ABSTRACT

Objective: To investigate the incidence of the second child's adverse birth outcome in Shaanxi Province and the relationship between sex of the first-born child and the adverse birth outcome of the second-born child. Methods: Data used in this study were derived from the prevalence and risk factors of birth defects in Shaanxi Province from 2010 to 2013. Descriptive epidemiological method was used to analyze the data of the second-born child's adverse birth outcome. Logistic regression model was employed to do regression analysis of the factors related to the second-born child's adverse birth outcome. Results: Large for gestational age infant and small for gestational age infant accounted for 15.88% and 12.27%, fetal macrosomia and low-birth weight accounted for 7.16% and 4.22%, premature delivery and birth defects accounted for 3.25% and 2.51%, while postmature infant accounted for 2.18%, respectively. Sex differences on large for gestational age infant, small for gestational age infant, fetal macrosomia and low-birth weight existed (P<0.05). Analysis of logistic regression model indicated that for the second-born child, having an elder brother compared with having an elder sister associated with an increased risk of small for gestational age (OR=1.251) and a lower risk of macrosomia (OR=0.808) and large for gestational age (OR=0.873). Conclusion: For the second-born child, having an elder brother compared with having an elder sister is associated with an increased risk of small for gestational age and a lower risk of macrosomia and large for gestational age.