Low birth weight, intrauterine growth restriction and risk of chronic kidney disease in adult age

Abstract

Background and aims: Studies have shown that adults with low birth weight (LBW) face an increased risk for chronic kidney disease (CKD), high blood pressure and cardiovascular disease (CVD). Previous Norwegian studies have shown that individuals with LBW more often develop kidney failure; however, there is a need for more knowledge regarding risk of more moderate kidney disease, such as chronic kidney disease (CKD).

Methods: This thesis consists of three studies that were conducted as retrospective registry-based cohort studies. Datasets were obtained through linkage of the Medical Birth Registry of Norway (MBR), Norwegian Population Registry (NPoR), Norwegian Renal Registry (NRR) and the Norwegian Patient Registry (NPR) (data available for 2008-2016 for the latter). We included all individuals born in Norway since 1967. For Paper I, we investigated the risk of kidney failure as registered in the NRR, and for Papers II and III, we investigated the risk of diverse forms of kidney disease as registered in the NPR. Relative risk (RR) estimates were obtained by Cox-regression or logistic regression statistics.

Results: In our studies, we were able to include about 2.6 million individuals. In Paper I, 1126 individuals developed kidney failure and individuals with LBW had a RR of 1.61 (95% CI 1.38-1.98) for kidney failure, and individuals with small for gestational age (SGA) had a RR of 1.44 (1.22-1.70). In Papers II and III, 4495 individuals had been diagnosed with CKD and 12,818 with other groups of kidney disease. LBW was associated with a RR of 1.72 (1.60-1.90) for CKD and SGA with a RR of 1.79 (1.65-194). These birth-related factors were more strongly associated with CKD than with other forms of kidney disease. In Paper III, we found that as compared the individuals who did not have LBW and who did not have a sibling with LBW, individuals who did not have LBW but who had a sibling with LBW had a RR of 1.33 (1.19-1.49), individuals with LBW but no siblings with LBW had a RR of 1.74 (1.55-1.95) and individuals with LBW and a sibling with LBW had a RR of 1.77 (1.54-2.04) for CKD.

Conclusion: In our cohort studies with a follow-up of 50 years, low birth weight and intrauterine growth restriction were found to be associated with an increased risk for both kidney failure and CKD. Taken together, our results support the hypothesis that intrauterine growth restriction (IUGR) increases the risk of CKD in adult life.