Chronic kidney disease and adverse pregnancy outcomes: a systematic review and meta-analysis.

OBJECTIVE: Limited evidence exists on the role that the cause of chronic kidney disease plays in determining pregnancy outcomes. The aim of this systematic review and meta-analysis was to examine the association between chronic kidney disease and adverse pregnancy outcomes by the cause and severity of chronic kidney disease where reported. The protocol was registered under the International Prospective Register of Systematic Reviews (CRD42020211925). DATA SOURCES: PubMed, Embase, and Web of Science were searched until May 24, 2021, supplemented with reference list checking. STUDY ELIGIBILITY CRITERIA: Studies that compared the pregnancy outcomes in women with or without chronic kidney disease were included. Two reviewers independently screened titles, abstracts, and full-text articles according to a priori defined inclusion criteria. METHODS: Data extraction and quality appraisal were performed independently by 3 reviewers. The grading of recommendations, assessment, development, and evaluation approach was used to assess the overall certainty of the evidence. Random-effects meta-analyses were used to calculate the pooled estimates using the generic inverse variance method. The primary outcomes included preeclampsia, cesarean delivery, preterm birth (<37 weeks' gestation), and small for gestational age babies. RESULTS: Of 4076 citations, 31 studies were included. Prepregnancy chronic kidney disease was significantly associated with a higher odds of preeclampsia (pooled crude odds ratio, 8.13; [95% confidence interval, 4.41-15], and adjusted odds ratio, 2.58; [1.33-5.01]), cesarean delivery (adjusted odds ratio, 1.65; [1.21-2.25]), preterm birth (adjusted odds ratio, 1.73; [1.31-2.27]), and small for gestational age babies (adjusted odds ratio, 1.93; [1.06-3.52]). The association with stillbirth was not statistically significant (adjusted odds ratio, 1.67; [0.96-2.92]). Subgroup analyses indicated that different causes of chronic kidney disease might confer different risks and that the severity of chronic kidney disease is associated with a risk of adverse pregnancy outcomes, as pregnancies with later stages of chronic kidney disease had higher odds of preeclampsia, preterm birth, and small for gestational age babies than those at earlier stages. The grading of recommendations, assessment, development, and evaluation certainty of the evidence overall was "very low". CONCLUSION: This meta-analysis quantified the associations between prepregnancy chronic kidney disease and adverse pregnancy outcomes, both overall and according to the cause and severity of the disease. These findings might support the clinicians aiming to counsel women having chronic kidney disease by allowing them to tailor their advice according to cause and severity of the chronic kidney disease. We identified the gaps in the literature, and further studies examining the effect of specific kidney diseases and other clinical characteristics (eg, proteinuria, hypertension) on adverse pregnancy outcomes are warranted.