Why newborn do loses 5-10 percent birth weight during the first few days after birth?

Newborns typically lose 5-10% of their birth weight in the first few days due to several factors, including the loss of excess fluid accumulated during pregnancy and the adjustment to feeding outside the womb. They may also lose weight as they begin to expel meconium and transition to regular feeding patterns. This weight loss is generally normal and usually stabilizes or reverses as the baby begins to feed effectively and gain weight. Most infants regain their birth weight by about two weeks of age.