Growth velocity before sudden infant death. Weight velocities of 136 infants who died from sudden infant death syndrome (SIDS) were compared with those of 136 controls matched for sex, birth weight, and type of feeding. It was found that the SIDS infants gained weight more slowly overall and that the differences were significantly different for infants who were not breast fed in the last two weeks in which it was possible to estimate their growth velocity. Breast fed infants had more periods of growth below the 25th centile than expected. These differences are unlikely to be useful in the prediction of which babies are likely to die from SIDS as there are frequent episodes of poor growth in infants who do not die. 