Pregnancy in CKD Stages 3 to 5: Fetal and Maternal Outcomes

Background

Prognostic criteria to inform women with moderate to severe renal insufficiency who wish to bear children are not well established.

Study Design

Longitudinal multicenter cohort study.

Settings & Participants

Nondiabetic white women with pregnancies proceeded beyond the 20th week and estimated glomerular filtration rate (GFR) less than 60 mL/min/1.73 m² (<1 mL/s/1.73 m²) before conception.

Predictors

Baseline GFR and proteinuria (exposure); other clinical characteristics at conception (covariates).

Outcomes & Measurements

Difference in GFR decreases before conception versus after delivery (mixed linear models); low birth weight (<2,500 g), and maternal renal survival (logistic and Cox regressions).

Results

49 women were studied. Mean serum creatinine and GFR at conception were 2.1 ± 1 (SD) mg/dL (186 ± 88 μmol/L) and 35 ± 12 mL/min/1.73 m² (0.58 ± 0.2 mL/s/1.73 m²), respectively. Overall mean GFR after delivery was less than before conception (30 ± 13.8 versus 35 ± 12.2 mL/min/1.73 m² [0.50 ± 0.23 versus 0.58 ± 0.20 mL/s/1.73 m²]; P < 0.001), but the rate of GFR decrease did not change (0.55 ± 0.8 versus 0.50 ± 0.3 mL/min/mo [0.0092 ± 0.013 versus 0.0083 ± 0.005 mL/s/mo]; P = 0.661). Independent of potential confounders, the combined presence of baseline GFR less than 40 mL/min/m² (<0.67 mL/s/m²) and proteinuria with protein greater than 1 g/d, but not either factor alone, predicted faster GFR loss after delivery compared with before conception (1.17 ± 1.23 versus 0.55 ± 0.39 mL/min/mo; difference, 0.62 mL/min/mo; 95% confidence interval [CI], 0.27 to 0.96 mL/min/mo [0.020 ± 0.021 versus 0.0092 ± 0.007 mL/s/mo; difference, 0.10 mL/s/mo; 95% CI, 0.005 to 0.016 mL/s/mo]). The presence of both risk factors, but not either alone, also predicted shorter time to dialysis therapy or GFR halving (N = 20; hazard ratio, 5.2; 95% CI, 1.7 to 15.9) and low birth weight (N = 29; odds ratio, 5.1; 95% CI, 1.03 to 25.6).

Limitations

Generalizability to other settings; study power.

Conclusion

In women with renal insufficiency, the presence of both GFR less than 40 mL/min/1.73 m² (<0.67 mL/s/m²) and proteinuria with protein greater than 1 g/d before conception predicts poor maternal and fetal outcomes.

Index Words: Angiotensin-converting enzyme (ACE) inhibitors, chronic kidney disease, fetal outcome, pregnancy, proteinuria, renal disease progression