The severity of preeclampsia in naturally conceived versus IVF-conceived pregnancies: a retrospective study

Pregnancies conceived using in vitro fertilization (IVF) significantly increase the risk of developing preeclampsia. One possible explanation is that embryos grown outside the body may implant differently compared to natural conceptions, potentially affecting placental development and increasing the risk of preeclampsia. Clinically, preeclampsia is classified into early-onset and late-onset forms, as well as severe and mild forms. Although some studies suggested that preeclampsia severity may be more pronounced in IVF-conceived pregnancies, the findings were controversial. In this retrospective study, we compared the severity of preeclampsia between naturally conceived and IVF-conceived pregnancies. A total of 498 preeclampsia cases were included, with 401 cases occurring in naturally conceived pregnancies and 97 in IVF-conceived pregnancies. The mean gestational age at delivery in the IVF-conceived group was 36 weeks, significantly earlier than that in the naturally conceived group (37 weeks, p = 0.0002). Additionally, 27 (28%) women in the IVF-conceived group developed early-onset preeclampsia, which was no statistical difference from the naturally conceived group (78, 19%, p = 0.0732). There was no significant difference in the proportion of severe preeclampsia between the two groups (16% vs. 23%, p = 0.1667). Additionally, gestational age at the onset of preeclampsia and the incidence of preterm birth were not different between the two groups after adjusting for important confounders, including maternal age, BMI, parity, and twin pregnancy. In conclusion, there is a known link between IVF conception and the increased risk of developing preeclampsia. Our study found that the severity of preeclampsia, once it occurred, did not differ between the two modes of conception.