The infant period is a time of extraordinary growth and development. In fact, infants typically double their birth weight by four to six months of age and triple it by the time they turn one. During their first year, infants increase their length by 50%, gaining about an inch per month for the first six months and a 1/2 inch a month from six months to twelve months.
Immediately following birth, however, an infant normally loses about 10% of her birth weight due to fluid loss and some tissue breakdown, according to the American Academy of Pediatrics. Within 7 days, infants typically gain that weight back.
A child’s parents influence a child’s size. Taller parents tend to have taller children. However, malnutrition, disease and other environmental factors can also influence a child’s physical growth. It’s also important to note that the rate of growth of breastfed and formula fed infants differ during the first year. Breastfed infants grow more rapidly during the first 6 months but less rapidly during the remainder of the first year, according to the American Academy of Pediatrics.
Pediatricians use standardize height and weight charts to track a child’s physical growth. There is one for boys and one for girls. Children are compared against their own growth rate to track their growth process and with other children of the same age and gender to track how they are growing in comparison to their peers. Ideally children follow the same growth pattern growing at the same growth rate with their height and weight being proportionate.