Abstract: ObjectiveTo explore whether adverse effects of pre-pregnancy body mass index(BMI)on hypertension disorders in pregnancy are moderated by gravidity.MethodsA total of 1 633 pregnant women who had antenatal care in their early pregnancy and delivered from February 2011 to December 2012 were selected as study subjects.The associations of parity and pre-pregnancy BMI with hypertension disorders in pregnancy were evaluated with Chi-square analysis and logistic regression.ResultsThe average pre-pregnancy BMI for the pregnant women was 20.20(2.418 kg/m²).Based on the pre-pregnancy BMI,367 women were classified as emaciation(22.5%),1 153 as normal(70.6%),and 113 as overweight or obese(6.9%).Of the women, 936(57.3%)were nulliparous and 697(42.7%)were multiparity.Univariate analysis showed that the risk of hypertension disorders among pre-pregnancy overweight or obese pregnant women increased with the odds ratio(OR)of 2.722(95% confidence interval95%CI=1.074-6.900,P=0.035)and 4.356(95%CI=1.865-10.171,P=0.001).After adjusting for confounding factors such as pregnant chronological age,education level,and job category,multivariate analysis showed that parity was a risk factor of hypertension disorders in pregnancy for pre-pregnancy overweight or obese pregnant women(for multiparity:OR=3.535,95%CI=1.472-8.491;P=0.005).ConclusionPre-pregnancy overweight or obese pregnant women who had more parity are at a higher risk of hypertensive disorders in pregnancy.