A Normal-term newborn typically loses 5 to 8% of their birth weight during the first few days of life.  They regain this weight by the end of the first 2 weeks.  After this period of time, newborns typically gain at least 1/2 to 1 ounce per day during the first 2 months, and 1 pound per month after that.  This weight gain typically results in a doubling of birth weight by age 5 months and a tripling by 1 year.

Leigh Gistinger, CPNP