Abstract： Objective To explore the influence of maternal pre-pregnancy body mass index(BMI)on the risk of developing preeclampsia(PE)after assisted reproductive technology(ART)treatment,as well as the dose-response relationship between the two.Methods The study included women who gave birth and re-ceived ART treatment(including in vitro fertilization-embryo transfer and artificial insemination)in our hospital from September 2020 to August 2022.Among them,one hundred and forty-nine were diagnosed with PE(PE group,case group)and eight hundred and sixty-eight patients were not diagnosed with PE(non-PE group,control group).Basic information of the women,including age,pre-pregnancy height and weight,parity,education level,occupation,address,mode of delivery,and clinical diagnosis,was collected through an electronic medical record information system.The relationship between maternal pre-pregnancy BMI and PE,as well as the dose-response relationship between the two,was analyzed using univariate anal-ysis and multiple logistic regression models.Results A total of one thousand and seventeen women met the inclusion criteria,of whom 56(5.5％)were underweight,288(28.3％)were overweight,and 106(10.4％)were obese.Univariate analysis showed that the maternal pre-pregnancy BMI in the PE group was higher than that in the non-PE group(P＜0.05).When compared to the normal BMI group,the risk of PE was reduced when the BMI was＜18.5(P＞0.05).However,the risk of PE increased with increasing BMI when the pre-pregnancy BMI was ≥25(P＜0.05),indicating a dose-response relationship between pre-preg-nancy BMI and the risk of PE(linear trend P＜0.05).Multiple logistic regression analysis showed that as the pre-pregnancy BMI increased,the risk of PE also increased.Compared to the normal BMI group,women with lower pre-pregnancy BMI(＜18.5)had a reduced risk of developing PE(OR=0.76,95％CI:0.26-2.25),while women who were overweight(OR=1.67,95％CI:1.10-2.54,P＜0.05)and obese(OR=2.99,95％CI:1.77-5.02)before pregnancy had a significantly increased risk of developing PE(P＜0.05).Conclusion There is an association between maternal pre-pregnancy BMI and PE in women under-going ART treatment,and there is a dose-response relationship between maternal pre-pregnancy BMI and the risk of PE.The higher the pre-pregnancy BMI,the higher the risk of developing PE.These findings support the clinical recommendation for overweight or obese women to lose weight before receiving ART treatment.