RESUMEN
Objective To identify the association between gestational weight gain and birth weight over the past 9 years in Kunshan city,Jiangsu province,China.Methods This population-based study was conducted between 2001 to 2009.Data were retrieved from Perinatal Monitoring System of Maternal and Child Health Care Hospital of Kunshan.The study population consisted of 33 631 women and singleton live fetus.Gestational weight gain was defined as the total weight gain during the last and first prenatal care program and divided by the interval weeks.Results From 2001 to 2009,the average incidence of low birth weight was 1.86％,while the average incidence of macrosomia was a bit higher,fluctuating around 8.47％.On those underweight mothers,after adjustment for potential confounders,and stratified by the BMI levels,which were evaluated at the first prenatal care program,we found that weight gain in the 3rd and 4th intervals,could reduce the risk of low birth weight (less than 2500 g).With those mothers with normal-weight,weight gain in the 2 rid,3 rd and 4th intervals,would reduce the risk of low birth weight.Risks in the 4th quantile among underweight and normal-weight group were prevalence odds radio (POR) 95％CI:0.51 (0.32-0.80) and 0.58 (0.42-0.79),respectively.The risks showed a significant downward trend in underweight and normal- weight groups with increased gestational weight gain.As for macrosomia (≥4000 g),the risks increased (POR 95％CI) 4.69(2.82-7.81 ) in underweight,4.15 (3.43-5.03) in normal-weight,in overweight,3.64 (2.62-5.06) and 1.96 (1.48-2.60) in obese mothers with increased levels of gestational weight gain.Trend tests indicated that the risks of marcosomia increased in all levels of BMI,with the increase of gestational weight gain.Conclusion Findings from this population-based study suggested that gestational weight gain could reduce the risks of low birth weight among underweight and normal-weight groups,while increase the risks of macrosomia in all parturients,as compared with lowest levels of gestational weight gain.