Background In the last few years there has been an increase in case reports of hypernatremic dehydration in breast-fed newborns. Insufficient intake has an important role in the pathophysiology of this condition.

The aim of this study was to evaluate breast-fed neonates admitted for hypernatremic dehydration.

Methods Retrospective study conducted by clinical chart review of breast-fed neonates with hypernatremic dehydration, between March 2002–March 2008.

Results 19 cases were identified (0.44% of neonatal intermediate care hospitalizations): 47% female and 53% male. Annual distribution revealed a higher number of cases in 2008: 26.3% in only 3 months. BW ranged from 2370 g to 4145 g (median 3000 g), and gestational age from 35 w to 40 w (mean- 38 w). Vaginal delivery was the most frequent. Maternal age ranged from 16 to 38 years old (mean 29 y), the majority of mothers being primiparous (79%). Admissions were made through the emergency department in 68.4% of cases. Main reasons for seeking medical attention: poor oral intake (32%), weight loss (26%) and jaundice (26%). Age at admission ranged from 2 to 21 days (median-4 days). Percentage of weight loss: 6.7%–40%, median 11%. Dehydration signs were absent in 42%. Na+ values:146–196 mEq/L, median 152 mEq/L. Co-morbidities were found in 74% of patients, jaundice being the most frequent (100%). Intravenous fluids were administered in 89%. Acute neurological complications were found in 21%. There were no deaths.

Discussion Breast-feeding associated hypernatremic dehydration seems to be a consequence of breast-feeding difficulties in inexperienced mothers. This strengthens the need for better support from health care professionals in education and follow-up monitoring of breast-feeding techniques.