From the Guidelines
Newborns typically lose 5-10% of their birth weight during the first week of life, with breastfed babies often losing slightly more than formula-fed infants. This weight loss is normal and occurs primarily due to fluid shifts, limited initial milk intake, and the passage of meconium 1. To prevent excessive weight loss (defined as more than 10% of birth weight), ensure frequent breastfeeding sessions (8-12 times per day) with proper latch and positioning, or appropriate formula feeding if not breastfeeding. Some key points to consider include:
- Monitoring for adequate hydration by tracking wet diapers (at least 6 per day by day 5) and bowel movements
- Early and regular lactation support to help establish effective breastfeeding
- Skin-to-skin contact to promote successful feeding and milk production
- Weight should stabilize by days 4-5 and return to birth weight by 10-14 days of life If weight loss exceeds 10%, or if the baby hasn't regained birth weight by two weeks, medical evaluation is necessary as supplementation may be required 1. It's also important to note that individual patient needs may deviate from generally recommended intakes, depending on clinical circumstances such as fluid retention, dehydration, or excessive water losses 1. In preterm neonates, restricted Na intake has positive effects on oxygen requirements and the risk of later bronchopulmonary dysplasia, but may also increase the risk of hyponatremia 1. Electrolytes (Na, Cl, and K) should be supplied starting during the initial loss of body weight, with Cl intake slightly lower than the sum of Na and K intakes to avoid excessive Cl intakes and risk of iatrogenic metabolic acidosis 1. Overall, close clinical monitoring is necessary to avoid inadequate intakes, oliguria, electrolyte disturbances, and acidosis, and to ensure that the newborn's weight loss is within the normal range 1.
From the Research
Normal Weight Loss Range for Newborns
- Newborns typically lose 5-10% of their birth weight during the first week of life, with the nadir of lost birth weight occurring on Days 2,3, or 4 after birth 2, 3, 4.
- The mean weight loss among neonates is usually 6% to 7% of birth weight by 2 days after birth, and 7% to 8% by Day 3 4.
- Some studies have reported a wider range of mean infant weight loss, from 3.79% to 8.6% 5.
Factors Influencing Weight Loss
- The percentage of weight loss at birth and the rate at which this weight is regained can be influenced by multiple factors, including feeding type (breastfed or formula-fed) and mode of delivery (vaginal or cesarean) 2.
- Exclusively breastfed newborns may lose 10% or more of their birth weight, but this does not necessarily indicate a need for formula supplementation 2, 4.
Preventing Excessive Weight Loss
- Close monitoring of newborn weight and hydration status can help prevent excessive weight loss and related complications, such as jaundice, hypernatremia, and hypoglycemia 6.
- Ensuring adequate milk intake, either through breastfeeding or supplementary feeding, is crucial to prevent neonatal starvation and deprivation 6.
- The use of formula as a supplementary milk can be an effective way to mitigate risks associated with breastfeeding insufficiencies, particularly in cases where mothers' milk is not yet in or is insufficient 6.