Gestational Changes in eGFR among Patients with CKD

Background: Chronic kidney disease (CKD) affects ~3% of women of childbearing age and is a risk factor for adverse pregnancy outcomes. In normal pregnancy, glomerular filtration rate (GFR) increases by 40-50%. Pregnant patients with CKD may have a blunted gestational increase in GFR. This study aimed to explore if lower baseline eGFR is associated with a lower gestational increase in eGFR among pregnant patients with CKD. Methods: This was a single-center retrospective study of pregnant women age ≥18 who received care at a multidisciplinary high-risk obstetric nephrology clinic between 2011-2023. All subjects had CKD, defined as eGFR < 60 ml/min/1.73m2 or urine protein:creatinine ratio (UPCR) >150 mg/mg prior to pregnancy, or UPCR >300 mg/mg prior to 20 weeks gestation. eGFR was calculated using the 2021 CKD-EPI Cr equation. Baseline eGFR was calculated from the last serum Cr prior to and within 2 years of pregnancy. Gestational % change in eGFR was calculated from the baseline eGFR and the peak mid-pregnancy eGFR, measured between 13-28 weeks gestation. Pearson’s correlation was used to assess the correlation between baseline eGFR and gestational change in eGFR. Results: 47 patients were included in the study. 5 (10.6%) had diabetes mellitus, and 15 (31.9%) had chronic hypertension. At the initial prenatal visit, 41 (87.2%) had proteinuria, 13 (37.1%) had eGFR 30-59, and 2 (5.7%) had eGFR 15-29. Median eGFR prior to pregnancy was 91.2 ml/min/1/73 m2 (IQR 58.8-119.0), and median peak eGFR during pregnancy was 105.2 (IQR 59.6-133.9). The median absolute change in eGFR was 11 ml/min/1.73 m2 (IQR 3.9-18.6), and median percent change was +13% (IQR +4-26.9%). There was no correlation between baseline eGFR and gestational change in eGFR (Pearson correlation coefficient -0.065, p=0.6647). 18 patients (39.1%) developed preeclampsia. Conclusion: We found no correlation between baseline eGFR and gestational change in eGFR in patients with CKD. Limitations included a small number of patients with very low eGFR. Our patients with CKD had a smaller gestational increase in GFR than has been reported in pregnant patients with normal kidney function.