Objective To investigate the pre-pregnancy body mass distribution of pregnant women and to analyze the correlation between pre-pregnancy body mass index (BMI) and hypertensive disorders in pregnancy.

Methods Clinical data were collected from 2 618 full-term singleton pregnant women.According to the pre-pregnancy BMI, they were divided into 234 cases in the low body mass group, 1 610 cases in the normal body mass group, 545 cases in the over group, 128 cases in the Ⅰ-degree obese group, and 101 cases in the Ⅱ-degree obese group.The general information and maternal conditions of pregnant women in the 5 groups were compared, and the correlation between pre-pregnancy BMI and hypertensive disorders in pregnancy were analyzed.

Results There was no statistically significant difference in the age, height, pregnancy, and delivery of pregnant women in the 5 groups (P>0.05).There was a statistically significant difference in the number of days of delivery and mode of delivery of pregnant women in the 5 groups (P < 0.05).The incidence of hypertensive disorders of pregnancy increased with the increase of pre-pregnancy BMI (P < 0.05).The risk of hypertensive disorders of pregnancy increased in pregnant women with pre-pregnancy overweight, Ⅰ-degree obesity and Ⅱ-degree obesity (P < 0.05), and the risk of pregnancy hypertension, preeclampsia, and severe preeclampsia in the Ⅱ-degree obese group was higher than that in the other groups, which was 5.19, 8.77 and 7.97 times higher than that of normal-weight pregnant women, respectively.The relative risk of pre-pregnancy overweight and obesity was >1, the 95%CI did not include 1, and pre-pregnancy BMI ≥24 kg/m² was a risk factor for hypertensive disorders in pregnancy.

Conclusions Pre-pregnancy overweight and obesity are risk factors for hypertensive disorders in pregnancy, and weight management should be strengthened for women of childbearing age, especially overweight and obese women, before and during pregnancy.