Early-mid pregnancy renal parameters and adverse pregnancy outcomes in women with early stage CKD: a case series

TL;DR

This study examines how early pregnancy kidney markers in women with early stage CKD relate to adverse pregnancy outcomes like preterm birth and low birth weight.

Contribution

The study identifies that traditional mid-pregnancy kidney markers do not reliably predict adverse outcomes in early stage CKD pregnancies.

Findings

86% of women with early stage CKD had one or more 'red flag' kidney markers during pregnancy.

Despite these markers, there was no significant link between them and adverse pregnancy outcomes.

49% of pregnancies in women with early stage CKD had a composite adverse outcome.

Abstract

Early CKD may affect pregnancy outcomes, but identifying women at most risk remains challenging. We aimed to understand the predictive role of clinical parameters in early-mid pregnancy in women with early stage CKD.

Women with CKD stage 1–3 with a pregnancy > 20 weeks gestation between 2018 and 2023 were evaluated for ‘red flag’ markers previously linked with risk of adverse pregnancy outcomes: failure of ≥ 10% fall in serum creatinine; urinary protein: creatinine ratio (uPCR) ≥ 30 mg/mmol in second trimester; lack of physiological fall in blood pressure by mid-pregnancy. The relationship between these red flags and a composite adverse pregnancy outcome of gestational age < 37 weeks, birth weight < 2500 g and pre-eclampsia was determined.

Of 38 mothers with 47 deliveries, 72% of pregnancies were in women with stage 1 CKD, 38% had hypertension and 19% had pre-eclampsia. Infants had median birth weight 2895 g (IQR: 2460–3170) and median gestational age 37.3 weeks (IQR 35.8–38). Serum creatinine did not fall ≥ 10% in 66% (n = 27/41) of women, uPCR was ≥ 30 mg/mmol in 69% (n = 24/35) and blood pressure did not fall in 73% (n = 24/33). Eighty-six percent had one or more ‘red flags’. The composite adverse pregnancy outcome occurred in 49% (n = 22/45). Women exhibiting any early-mid pregnancy red flags did not have increased rates of composite adverse pregnancy outcome (no creatinine fall, composite adverse pregnancy outcome n = 15, p = 0.176; proteinuria n = 15, composite adverse pregnancy outcome p = 0.066; no blood pressure fall, composite adverse pregnancy outcome n = 12, p = 1.00).

The high rate of composite adverse pregnancy outcome in early stage CKD was not associated with traditional mid-pregnancy red flags. Best models of care for this cohort remain uncertain.

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