Why are babies getting heavier? Comparison of Scottish births from 1980 to 1992

Over the past decade the weights of babies born in the United Kingdom have been increasing,1 which may have implications for the pattern of adult disease.2 From 1980 to 1992 the mean birth weight of live singleton births in Scotland increased steadily from 3326 g to 3382 g. We investigated factors that may explain this trend. The distribution of gestational age has changed noticeably over the past decade because of the gradual introduction of its assessment by ultrasonography.3 In 1980 around 42% of all live births occurred at 40 weeks' gestation; by 1992 this had fallen to 32%. Thus trends in birth weights adjusted for gestation may be misleading and are not considered here. We assessed data on live, singleton births in …