[A longitudinal study on the relationship between pre-pregnancy urolithiasis and pre-eclampsia: the mediating effect...

Objective: To evaluate the association between pre-pregnancy urolithiasis and pre-eclampsia and to further explore the mediating effect of hyperuricemia in early pregnancy on the relationship between urolithiasis and pre-eclampsia. Methods: Pregnant women attending prenatal care in early pregnancy at 7 Maternal and Child Health Hospitals in Hunan Province from August 2014 to December 2019 were recruited to construct a cohort of early pregnancy. The paper questionnaire collected demographic data on pregnant women, pre-pregnancy disease history, and living habits, etc. Besides, the early pregnancy laboratory examination and pregnancy outcome for this pregnancy were derived from the hospital's electronic medical record system. Logistic regression models were used to analyze the association between pre-pregnancy urolithiasis and pre-eclampsia, and causal mediation analysis was used to investigate the mediating role and magnitude of hyperuricemia in early pregnancy in the association pathway between pre-pregnancy urolithiasis and pre-eclampsia. Results: A total of 33 579 naturally conceived singleton pregnant women were included in the analysis, of which 3 230 cases (9.6%) had hyperuricemia in early pregnancy, and 666 cases (2.0%) had pre-eclampsia. The multivariate logistic regression analysis indicated that pre-pregnancy urolithiasis increased the risk of pre-eclampsia (OR=2.65, 95%CI: 1.56-4.51). Mediation analysis showed that after controlling for confounders, hyperuricemia in early pregnancy could mediate the association between pre-pregnancy urolithiasis and pre-eclampsia, with a mediation effect proportion of 46% (P<0.05). Conclusions: Pre-pregnancy urolithiasis is an independent risk factor for pre-eclampsia, and early pregnancy hyperuricemia has a certain mediating effect between urolithiasis and pre-eclampsia.