Hydration status of exclusively and partially breastfed near-term newborns in the first week of life.

An in-hospital prospective, observational cohort study was conducted to assess the effects of type of feeding (exclusively breastfed [EBF] vs partially breastfed [PBF]) on the hydration status of near-term newborns in the first week of life. A total of 205 babies of 35 to 37 weeks of completed gestation were enrolled (82 in the EBF group and 123 in the PBF group). The overall incidence of significant weight loss (>or=10%) was 18% with no significant difference between EBF and PBF groups (18.3% vs 17.9%, P=.94). The incidence of hypernatremia (serum NA>or=150 meq/L) was 2.4% in the EBF group and 5.7% in the PBF group (P=.32). The factors associated with significant weight loss in the total cohort were having a mother with previous negative breastfeeding experience (adjusted odds ratio [OR]=16.5, 95% confidence interval [CI]=2.1-115.7), exposure to phototherapy (adjusted OR=9.0, 95% CI=2.5-31.8), and cesarean delivery (adjusted OR=6.7, 95% CI=2.3-19.7).