Pregnancy outcomes and risk factors analysis in patients with chronic kidney disease: a nested case-control study

Chronic kidney disease (CKD) poses significant risks during pregnancy. Accurate early risk prediction remains challenging due to physiological changes, disease heterogeneity, and limitations of various independent renal markers in pregnancy. The aim of this study is to explore the clinical and laboratory variables in early pregnancy that can predict adverse neonatal and maternal outcomes, thereby facilitating the grading management of CKD.

A nested case-control study was conducted at Zhongnan Hospital, Wuhan University (2018-2024). We enrolled 187 pregnant women diagnosed with CKD before 12 weeks gestation and 187 controls who were matched in terms of age and major comorbidities but without CKD. CKD staging was based on the first trimester estimated glomerular filtration rate (eGFR) using the CKD-EPI equation and urine albumin-to-creatinine ratio (uACR). Adverse maternal outcomes(AMOs) and adverse neonatal outcomes (ANOs) were compared. Multivariable logistic regression identified predictors.

Key findings showed significantly higher rates of ANOs in CKD patients (61.5% vs. 16.04%, P < 0.01), including preterm birth (48.66% vs. 6.95%, P = 0.023), and SGA (13.90% vs. 2.67%, P < 0.001). AMOs occurred in 48.1% of CKD patients (vs. 4.81% controls, P < 0.001), predominantly preeclampsia (43.85%). Multivariable analysis identified independent risk factors for ANOs: new-onset CKD (OR = 4.447, 95%CI1.949-10.147, P < 0.001), severe proteinuria (OR = 2.487,95%CI 1.112-5.565,P = 0.027), and chronic hypertension (OR = 8.127, 95%CI 2.491-26.512,P = 0.001). These three factors can also affect the outcome of AMO. In addition, the maternal age(OR = 0.886, 95%CI 0.805-0.975, P = 0.013) and a creatinine level (≥ 90µmol/L)(OR = 5.898, 95%CI 1.468-23.702, P = 0.012)are also influencing factors for AMO.

CKD pregnancies pose significantly elevated risks for maternal and neonatal complications. Our findings identify specific early-pregnancy markers - namely serum creatinine (Scr) levels and severe proteinuria (uACR > 300 mg/g) - as critical thresholds for risk stratification, highlighting the necessity for intensified monitoring in this high-risk population.