Both maternal and paternal risk factors for term singleton low birthweight infants in rural Chinese population: a population-based, retrospective cohort study

No large population-based study has focused on both maternal paternal risk factors for low birthweight (LBW) in China. We aimed to identify parental risk factors associated with LBW.A population-based, retrospective cohort study was conducted on 202,725 singleton infants at 37–42 weeks. These term singleton newborns were classified as LBW with birthweight ≤2500 g(TLBW) and normal birthweight between 50th to 97th percentile (TNBW 50th–97th) according to Chinese singleton norms. Multiple logistic regression analyses were used to find those parental risk factors of LBW by comparing two groups. TLBW and TNBW(50th–97th) occupied 4.8% and 70.8% of the study population, respectively. Logistic regression showed a significant association with positive maternal hepatitis B surface antigen (RR = 1.979, P = 0.047), irregular folic acid intake (RR = 1.152, P = 0.003), paternal history of varicocele (RR = 2.404, P = 0.003) and female babies (RR = 1.072, P = 0.046). Maternal smoking, hypertension and history of stillbirth were found related to LBW but no statistically significant. Positive maternal hepatitis B surface antigen, irregular folic acid intake, paternal history of varicocele had a negative effect on birth weight. Measures are necessarily taken to avoid them to improve pregnancy outcomes. Further studies should be done to investigate each detailed risk factors on LBW.