Abstract: Objective To describe and analyze the trend and determinants of gestational weight gain (GWG) in pregnant women in Zhoushan city of Zhejiang province from 2000 to 2014. Methods The pregnant women were divided into three groups according to their GWG (adequate, excessive and inadequate). The trends of GWG were analyzed with trend 2 test and determinants of GWG were analyzed using multivariate linear regression and multivariate logistic regression models.Results The mean GWG was 16.04 kg in the pregnant women from 2000 to 2014, the differences in annual average weight gain was not significant. Among the pregnant women, 3 886 (13.90%) had inadequate GWG and 12 433 (44.40%) had excessive GWG. The regression analysis suggested that overweight and obese women before pregnancy were more likely to have excessive GWG (OR=14.49, 95% CI:11.07-18.98). Meanwhile, women who became pregnant in autumn (OR=2.72, 95% CI:2.43-3.05) or in winter (OR=2.47, 95% CI:2.21-2.77) were more likely to have inadequate GWG during pregnancy. Other factors independently associated with GWG included age, education level, occupation and gestational week.Conclusion The GWG was in an upward trend before 2007 and in a downward trend after 2007 in local pregnant women. Pre-pregnancy BMI, education level and pregnant season were the main factors influencing GWG. It is necessary to strengthen the health education in pregnant women about rational diet, exercise and body weight control before and during pregnancy to improve maternal and child health.