Birth weight doubling and tripling times: an updated look at the effects of birth weight, sex, race and type of feeding.

Data were collected on 335 infants from birth to age two years whose families were all subscribers to a prepaid medical care plan. Birth weights were not significantly different by race or gender. Doubling time (DT) was significantly later than that reported in the mid-70s. Tripling time (TT) was significantly later than that calculated from the National Center for Health Statistics growth charts. Birth weight was the most significant factor for both DT and TT. Gender significantly affected DT only. Race was directly significant only for DT, but became significant for DT and TT when adjusted for gender and type of feeding. Type of feeding was not significant. The group which tripled birth weight the earliest had a higher percentage of fatter infants and suggest early TT may be useful to indicate infants at risk for obesity.