The sex-specific associations between birth weight and the risk of chronic kidney disease (CKD) later in life remain controversial. This study aimed to examine the shape of the relationship between birth weight and the risk of CKD in men and women.

A total of 277,252 participants free of CKD at baseline from the United Kingdom Biobank (UKB) prospective cohort were included in the analysis. Cox proportional hazard regression model was used to estimate the association between birth weight and the risk of incident CKD with adjustment for potential confounders.

During a median follow-up of 11.9 years, we identified 13,030 (4.7%) CKD cases. Compared with normal birth weight (2.5–4.0 kg), low birth weight (LBW, <2.5 kg) was associated with an 11% higher risk of CKD in men (adjusted hazard ratio [HR]: 1.11 [95% CI 1.01–1.21]) and a 27% higher risk of CKD in women (HR: 1.27 [1.19–1.36]) (p for interaction = 0.02). High birth weight (HBW, >4.0 kg) was associated with an 11% lower risk of CKD (HR: 0.89 [0.83–0.95]) in men but not in women (HR: 0.96 [0.89–1.04]) (p for interaction = 0.13). Furthermore, the LBW-CKD association was stronger in obese (HR: 1.28 [1.18–1.39]) than in nonobese participants (HR: 1.16 [1.09–1.24], p for interaction = 0.03).

We found an L-shaped relationship between birth weight and the risk of CKD in women but a linear shape in men. The LBW-CKD association was mitigated to some extent by maintaining healthy body weight in adulthood. Our findings support the notion that the CKD risk should be managed from a lifecycle perspective.