New research, published in The Journal of Pediatrics, used data going back to 1929 to track babies' sizes at birth and beyond, and found that those born after 1970 were heavier and longer than babies born in earlier decades.
‘What would have been considered a big kid in the 1930s would not have been considered a big kid today,’ said Ellen Demerath, one of the study's authors and an associate professor in the University of Minnesota.
Big guy: A study of babies born in southwestern Ohio since 1970 tend to be one pound heavier than they were in the 1920s and 1930s
But by age one, most babies were about the same size as counterparts in previous generations, suggesting that babies born smaller in the past experienced faster catch-up growth in their first year of life to arrive at similar average weights as the modern infants.
To test those ideas, Ms Demerath and her fellow researchers used data from a long-term study in Ohio of babies born since 1929 and their mothers.
The 620 babies they followed were weighed and measured from birth to age three, and all were of European ancestry.