Determinants of weight changes during the first 96 hours of life in full-term newborns.

BACKGROUND: Newborn weight loss (NWL) in the first 3 days of life is around 6 percent of birthweight (BW). We aim to describe the determinants of an excessive and insufficient NWL in the first 96 hours of life.

METHODS: A sample of 1,288 full-term singletons without congenital abnormality belonging to Generation XXI birth cohort was selected. Newborns were recruited in 2005-2006 at all public units providing obstetrical and neonatal care in Porto, Portugal. Information was collected by face-to-face interview and additionally abstracted from clinical records. Anthropometrics were obtained by trained examiners and newborn weight change (NWC) was estimated as (weight-BW)/BW × 100. We categorized NWL as excessive (below 10th percentile of the sample distribution of NWC: ≤-9.4% of BW), normal (between 10th and 90th percentiles: -9.3 to -4.2%) and insufficient (above 90th percentile: ≥ -4.1%). Adjusted odds ratios (OR) and 95 percent confidence intervals (CI) were calculated using multinomial regression models.

RESULTS: Excessive NWL was positively associated with maternal age ≥40 years (OR = 3.32, 95%CI 1.19-9.25), maternal education (OR = 1.04, 95% CI 1.00-1.09), cesarean delivery (OR = 2.42, 95% CI 1.12-5.23), and phototherapy-treated jaundice (OR = 1.69, 95% CI 1.00-2.87). Insufficient NWL was positively associated with low BW (OR = 2.68, 95% CI 1.13-6.33), and formula/mixed feeding (OR = 1.74, 95% CI 1.13-2.66).

CONCLUSION: Excessive NWL was positively associated with maternal age and education, cesarean delivery, and phototherapy-treated jaundice. Insufficient NWL reflected child's feeding. As breastfed newborns did not lose weight excessively, but newborns with formula/mixed feeding had insufficient NWL, our study supports that breastfeeding provides excellent nutrition during this period.