In reply to Kathy Dettwyler's post regarding "growth charts for preemies", the following information may be helpful. In the just-published WHO Expert Committee report on "Physical status: the use and interpretation of anthropometry", the sex-specific, single/twins curve developed by Williams et al. (1982) is recommended for use in measuring birth weight-for-gestational age among *all* infants, i.e. children less than 12 months of age. The 10th percentile of the curve should be used for classifying small for gestational age. The 3 figures in question--birth weight percentiles and perinatal mortality rates (per 1000) for single female, single male, and multiple births--are provided on pp. 146, 147 and 148, respectively, of the report, which is No. 854 in the WHO Technical Report Series, Geneva, World Health Organization, 1995 (452 pages). Jim Akre, Nutrition unit, WHO, Geneva