[Twins: interpretation of height-weight curves at birth]

Weight, head circumference and body length curves were established with the data at birth of 770 twins born alive in our hospital. Those curves were compared with the Gairdner-Pearson curves realized on a population of singleton newborns. The twin weight curve shows the expected fall down from 32 weeks of gestation. More than 50% of twins would have been qualified as small for dates on the Gairdner standard for singletons. The head circumference and the body length curves show few differences, except a late fall down, significant from 39 weeks. So the normal twin shows usually an "asymmetrical" hypotrophy if compared with a general newborn population standard. The general weight standards do not allow to assess the normality of a twin and to suspect other reasons of fetal growth restriction that could also be present. These considerations plead for the use of specific twin charts. Yet the evaluation of twins on the general standards has still a place to estimate the immediate and at long-term adverse outcomes of fetal growth restriction. The evaluation of twin measurements would not be completed without the assessment of the weight discordancy inside the twin couple, as a risk factor of morbidity and mortality.