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

Background: 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.

Methods: 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.

Results: 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).

Conclusions: 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.