Birthweights in Iceland 70 years apart

Birthweights of 389 babies born in 1901-1910 and 6 303 born in 1972-1981 were compared. There had been a mean increase in birthweight of 85 g and the prevalence of low birthweight had fallen from 5.6% to 3.3%. It is unlikely that this apparent secular increase in birthweight is an artefact due to different methods of weighing. Probably an increase in maternal height accounts for much of the increase in birthweight rather than any other improvement in the quality of the intrauterine environment.