Reduced Kidney Mass Associated with Higher Preterm Delivery Risk

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For pregnant women, even small reductions in kidney mass are associated with shorter gestation times and increased risk of preterm delivery, according to a recent article in Kidney International.

Using an observational database from two Italian centers, the researchers identified 529 patients with a diagnosis of tubulointerstitial kidney disease and liveborn singleton infants. Of these women, 421 had stage 1 chronic kidney disease (CKD) without hypertension but with proteinuria of less than 0.5 g/day. A control group consisted of 842 women from a low-risk pregnancy cohort, propensity score-matched for age, parity, body mass index, ethnicity, and center. Pregnancy outcomes were compared between groups, with a focus on the effects of reduced maternal kidney mass.

Time to delivery was shorter in the group with tubulointerstitial kidney disease (range from quartile 1 to 3, 37.0 to 39.0 weeks) compared with the control group (range from quartile 1 to 3, 38.0 to 40.0 weeks). Delivery occurred before 37 weeks’ gestation in 10.8% of women with a history of acute pyelonephritis, 9.7% of those with other tubulointerstitial diseases, and 31.1% of those with a single kidney compared with 7.4% in the control group.

The same group with tubulointerstitial kidney disease had progressive reductions in neonatal birthweight compared with the control group. Pre-eclampsia occurred in 3.6% of women with CKD versus 1.7% of the low-risk control group.

The study provides new evidence regarding the association of tubulointerstitial disease with maternalfetal outcomes. “[E]ven a small reduction in functional kidney mass, such as a pyelonephritic scar, is associated with a shorter duration of pregnancy and an increased risk of preterm delivery,” the researchers write. They add that their findings “[highlight] the importance of being particularly attentive to all patients with even early CKD in pregnancy” [Piccoli GB, et al. Any reduction in maternal kidney mass makes a difference during pregnancy in gestational and fetal outcome. Kidney Int, published online January 29, 2024. doi: 10.1016/j.kint.2023.12.018].