Objective: To explore the appropriate weight gain during pregnancy and its relationship with the birthweight of offspring.
Methods: A total of 16 460 healthy pregnant women who delivered in Beijing Obstetrics and Gynecology Hospital and Haidian Maternity and Child Health Care Hospital in 2010 were recruited. All are singleton pregnancies. Conditions of babies and mothers were recorded, including maternal age, height, prepregnant weight, pregnant weight, gestational weeks on delivery, delivery mode and newborn birthweight. All the pregnant women were divided into underweight, normal weight and overweight group according to their prepregnant body mass index and the criteria of overweight and obesity for Chinese adults.Birthweight between 2500 g and 4000 g was defined as normal birthweight, and 2900 g to 3499 g was defined as appropriate birthweight.Logistic regression model and receiver operating characteristic (ROC) curve analysis were used to explore the recommended gestational weight gain (GWG).
Results: (1) The average GWG of the 16 460 women was (17.1 ± 4.9) kg, and the average birthweight of the babies was (3406 ± 400) g. Prevalence of low birthweight and macrosomia was 0.92% (152/16 460) and 7.55% (1 242/16 460), respectively.GWG of underweight (n = 3089), normal weight (n = 11 478) and overweight group (n = 1893) was (17.4 ± 4.6) kg, (17.3 ± 4.8) kg and (15.6 ± 5.3) kg, respectively. And GWG was positively related with the birthweight of offspring (P < 0.01).The differences of GWG, neonatal birthweight and macrosomia prevalence among the three groups are statistically significant (P < 0.01). (2) There are 8449 appropriate birthweight babies in the three groups.For their mothers in the underweight, normal weight and overweight group, the recommended range of GWG were 14.0-19.5 kg, 13.5-19.5 kg and 11.0-18.0 kg, respectively.The recommended GWG for all women was 16.0 kg. (3) According to the recommended GWG, low GWG will increase the risk of low birthweight (OR = 1.589, 95% CI: 1.085-2.326) and reduce the risk of macrosomia (OR = 0.500, 95% CI: 0.401-0.624). Excessive GWG will increase the risk of macrosomia (OR = 2.031, 95% CI:1.789-2.306), but will not lower the risk of low birthweight (OR = 1.168, 95% CI:0.774-1.764). (4) For the underweight, normal weight and overweight group, the range of GWG obtained by the receiver operating characteristic (ROC) curve analysis were 16.3-16.7 kg, 15.6-17.8 kg and 14.6-15.1 kg.For all the three groups, the range was 15.6-16.7 kg.The ranges obtained by the ROC curve analysis were all within the recommended range.
Conclusion: The GWG was positively associated with the birthweight of offspring, and the appropriate GWG was around 16.0 kg.