Growth An infant with failure to thrive will first demonstrate poor weight gain. ==> With continued insult, there will be reduced height/length growth and then, finally, reduced head circumference growth. After birth, infants will normally loose weight initially (particularly breastfed infants). Infants should regain their birth weight by 2 weeks of life. For the first 3 months, infants should gain ~30 grams a day (~1 oz / day). By 6 months, they should have doubled their weight. By 12 months, they should have tripled their weight. By 24 months, they should have quadrupled their weight.