During pregnancy, the natural arrangement is for baby to pile on some fat reserves in case the hard times come.
Mother nature has done this because some babies take time to get used to feeding. Many don't drink much the first day or two after birth, and just sleep the whole time. Your child has enough reserves and won't be hungry for this short period. Premature babies don't have many reserves, however, and must be watched carefully.
Your baby can indeed lose weight.
One reason for this potential weight loss is that babies can carry a lot of extra moisture which can be lost.
It's actually very normal for a baby to lose a little weight after birth. Usually the weight will drop a little in the first 3 to 4 days. After this, baby's weight should start to climb.
What baby can lose weight?
The maximum weight that a baby should lose is 7-10 percent of birth weight. The midwife or obstetrician will carefully monitor your baby's weight for a while. If baby stops eating, does not come to feed itself, or is too sleepy to feed, go to your obstetrician or GP.
From angelababy In Q&A