Adverse pregnancy outcomes in pregnant women with chronic kidney disease: A systematic review and meta-analysis

Background: Chronic kidney disease (CKD) is associated with an increased risk of adverse pregnancy outcomes, but the risk at different stages of CKD (defined by estimated glomerular filtration rate, eGFR) compared with women without CKD has not been quantified in large cohorts. Objectives: To quantify the association between CKD and adverse pregnancy outcomes according to CKD definition, CKD stage and presence or absence of diabetes. Search strategy: A systematic search of EMBASE and MEDLINE from inception to 5 January 2023. Selection criteria: English-language randomised controlled trials as well as cohort and case-control studies investigating adverse pregnancy outcomes in pregnant women with CKD. Data collection and analysis: Two reviewers conducted independent data extractions. A random-effects model was used to estimate risk. Main results: We included 19 studies with 3 251 902 women. Defining CKD using eGFR or serum creatinine produced results with greater effect size but wider confidence intervals. Compared with CKD stages 1-2, women with CKD stages 3-5 have a greater risk, but also greater imprecision in the risk estimate, of the following outcomes: pre-eclampsia (OR 55.18, 95% CI 2.63-1157.68, vs OR 24.74, 95% CI 1.75-348.70), preterm birth (OR 20.24, 95% CI 2.85-143.75, vs OR 8.18, 95% CI 1.54-43.46) and neonatal intensive care unit admission (OR 19.32, 95% CI 3.07-121.68, vs OR 9.77, 95% CI 2.49-38.39). Women with diabetic kidney disease, compared with women without diabetic kidney disease, have higher risks of maternal mortality, small-for-gestational-age neonates, pre-eclampsia and gestational hypertension. Conclusions: There is heterogeneity in the definition of CKD in pregnancy. Future studies should consider ways to standardise its definition and measurement in pregnancy.