Abstract:

Objective To describe and analyze the trends and determinants of birthweight in Beijing from 1996 to 2010. Methods 63 661 babies born in two hospitals in Beijing in 1996, 1997, 1998, 1999, 2000, 2005, 2010 were included to describe the trend of birthweight. The 11 006 birth records of those babies born in Beijing obstetric and gynecologic hospital in 2010 were collected to analyze the determinants of birthweight. The chi-square test and chi-square test for trend were used to estimate the distribution of categorical variables between groups, analysis of variance was used to test the difference of birthweight among years, linear regression analysis was applied to analyze the determinants of birthweight. Results The birthweight increased from 1996 to 2000 rapidly, and then decreased slowly. The mean value of birthweight in 2010 was 3 331 g, and it was higher than the national level. The linear regression analysis suggested that maternal age, body mass index, gestational weight gain, gravidity, parity, gestational weeks and gestational diabetes mellitus were positively correlated with birthweight, the gender of neonate (female), degree of maternal education, oligohydramnios, multiple gestation and gestational hypertension were negatively associated with birthweight. According to the American Institution of Medicine (IOM) guidelines on maternal health weight gain, more than half of the women had excessive gestational weight gain from 2000. Conclusions The birthweight increased rapidly before 2000, and then decreased slowly. Maintaining a normal maternal body mass index and an appropriate gestational weight gain, avoiding preterm birth and prevention of gestational diabetes mellitus and hypertension will be helpful to get normal birthweight.

Key words: Birthweight, Determinants, Preterm, Trend, Neonate