Impact of pre-conception kidney function on pregnancy outcomes

The prevalence and impact of early-stage chronic kidney disease (CKD) on pregnancy is poorly defined. We aimed to identify women with suspected early CKD pre-conception and assess the impact on maternofoetal outcomes.

We linked statewide perinatal datasets to pathology, renal registry and administrative datasets between 2005-23. We included women ≥18 years with one or more maternal serum creatinine measure within 5 years pre-conception or <30 days post-conception and examined maternofetal outcomes.

From 96 721 pregnancies (56 587 women), we included 42 212 pregnancies (33 116 women). Of those included, 644 had proteinuria or diagnosed kidney disease [and an estimated glomerular filtration rate (eGFR) >90 mL/min/1.73 m2], 2838 with an eGFR 60-90 mL/min/1.73 m2, and 30 with an eGFR 15-60 mL/min/1.73 m2. Only 6% of women with an eGFR <90 mL/min/1.73 m2 had formal quantitative measurement of albuminuria or proteinuria pre-conception. On multivariable analysis, women with suspected early CKD had an increased risk of gestation hypertension [odds ratio (OR) 1.21; confidence interval (CI) 1.04, 1.41] preeclampsia (OR 1.26; CI 1.03, 1.52), low birth weight (OR 1.15; CI 1.02, 1.31) and preterm delivery (OR 1.27; CI 1.03, 1.56) compared with those with normal kidney function.

We identified that 1 in 10 pregnancies had an eGFR <90 mL/min/1.73 m2, proteinuria or diagnosed kidney disease, warranting further research focussing on pre-conception kidney function assessments. While these women were at an increased risk of some maternofetal outcomes, the absolute risk remains small.