[Comparative analysis of high risk factors between early-onset pre-eclampsia and late-onset pre-eclampsia]

Objective: To explore the difference of high-risk factors between early-onset and late-onset pre-eclampsia, and to further understand high-risk factors of pre-eclampsia. Methods: Clinical data of pre-eclampsia pregnant women in 160 medical institutions in China in 2018 were retrospectively analyzed, including 8 031 cases of early-onset pre-eclampsia and 12 969 cases of late-onset pre-eclampsia. The proportion of high-risk factors, different body mass index (BMI) and age stratification between early-onset group and late-onset group were compared. Results: (1) Univariate analysis of high-risk factors: the proportions of high-risk factors in early-onset group and late-onset group were compared, and the differences were statistically significant (all P<0.05). Among them, the proportions of primipara and multiple pregnancy in early-onset group were lower than those in late-onset group, while the proportions of pregnant women with advanced age, irregular antenatal examination, obesity, family history of hypertension, pre-eclampsia, diabetes, kidney diseases, immune system diseases and assisted reproductive technology were higher than those in late-onset group. (2) Hierarchical analysis of BMI: the proportion of pregnant women with BMI≥24 kg/m² in early-onset group [48.2% (2 828/5 872) vs 45.5% (4 177/9 181), respectively; P=0.001] and the proportion of pregnant women with BMI ≥28 kg/m² in early-onset group [19.5% (1 143/5 872) vs 18.0% (1 656/9 181), respectively; P=0.028] were significantly higher than those in late-onset group. (3) Age stratification analysis: the proportion of pregnant women aged 35-39 years in the early-onset group [21.8% (1 748/8 023) vs 17.5% (2 110/12 068), respectively; P<0.01], the proportion of pregnant women 40-44 years old [6.8% (544/8 023) vs 5.4% (648/12 068), respectively; P<0.01], and the proportion of pregnant women ≥45 years old [0.7% (58/8 023) vs 0.5% (57/12 068), respectively; P=0.021] were significantly higher than those in the late-onset group. (4) Multivariate analysis: advanced age (≥35 years old), multiple pregnancy, irregular antenatal examination or transfer from other hospitals, family history of hypertension (including paternal, maternal and parental lines), previous history of pre-eclampsia, kidney diseases, immune system diseases (systemic lupus erythematosus, antiphospholipid antibody syndrome) and assisted reproductive technology pregnancy were the risk factors affecting the severity of pre-eclampsia (all P<0.05). Conclusion: Pregnant women with high risk factors such as age ≥35 years old, BMI ≥24 kg/m² before pregnancy, family history of hypertension, history of pre-eclampsia, chronic kidney diseases, immune diseases (mainly including systemic lupus erythematosus and antiphospholipid syndrome) and assisted reproductive technology are more likely to have early-onset pre-eclampsia.