[Are earlier birth weights different from current ones?]

A sample was taken from non-pathological Caucasian births in Amsterdam from 1972 until 1982. The methods replicated as closely as possible those applied by Kloosterman to births from 1931 until 1967 for the Amsterdam Growth Curves. Birth weight percentiles and confidence intervals were determined non-parametrically in groups distinguished by sex, order of birth and duration of pregnancy. The correlations among the weekly means and the extreme percentiles were tested from the 36th to the 43th pregnancy week. We found a strong correlation (r = 0.983) between our sample and the Amsterdam Growth Curves. The means in the latter sample exceeded ours by 48.5 grammes which equals the estimated clerical error of the birth weights of 50 grammes. There is no strong evidence that the birth weights have changed much in the Caucasian part of the Amsterdam population.