Breastfeeding does not protect against urinary tract infection in the first 3 months of life, but vitamin D supplementation increases the risk by 76%

Our goal was to determine if breastfeeding provides any protection against urinary tract infection (UTI) and if vitamin D supplementation imposes any additional risks for UTI in infants < 3 months of age. In this study, 40% of the children who had urine cultures were breastfed, and 18.7% of the children were exclusively breastfed. Twenty percent of all of the urine cultures tested positive, and this number was greater in females (22.5%) than in males (18.1%, P <.05). There was no significant difference between the rates of positive urine cultures in exclusively breastfed (22% vs 21%, nonsignificant [NS]) formula-fed infants. The relative risk of UTI with breastfeeding versus formula feeding was 1.03 (0.58-1.82), and any breastfeeding versus no breastfeeding was 0.92 (0.58-1.45). Vitamin D supplementation increased the UTI risk, with a relative risk of 1.76 (1.07-2.91, P <.05). However, only formula-fed infants showed an increased risk of UTI after vitamin D supplementation.