Fontanel size and epiphyseal ossification in neonatal twins discordant by weight.

Size of the anterior fontanel and ossification of the epiphyseal centers at the knee were measured in 13 "discordant" twin pairs. There was a highly significant (p smaller than 0.01) negative correlation between fontanel size and epiphyseal ossification. Severe intrauterine growth retardation (demonstrated by the lighter twin) may result in retardation of membranous as well as enchondral ossification.