All the babies that are born will lose weight within the first week of life. The weight loss should not be more than ten percent of the birth weight. For e.g, a baby who is born at three kilograms at birth is allowed up to 300 grams of loss in weight.. nnNormally, breast fed babies take slightly longer regain the birth weight. All babies will gain weight by ten days to two weeks. Babies who are born pre maturely, i.e around thirty seven weeks of gestation may take slightly longer time to regain birth weight.. nnA baby born at term which is thirty seven weeks plus will gain around twenty five to thirty grams per day or about one hundred and fifty to two hundred grams per week.. nnNormally, a baby will double birth weight by five to six months of age and triple their birth weight by about a year of age. To note that there is a wide spectrum in this. Some babies may do more than this while some lower. We have to take into account a lot of factors, make sure your baby is active, following all the milestones the baby should be doing like sitting, walking, having the head control, etc..