The SNOO Sleep Sack is designed to be loose enough in the hips to allow the infant’s legs to
bend and open at the knee and the hips to flex and abduct (“frogging out”). Both the SNOO
Sleep Sack and Sleepea are listed as hip safe by the International Hip Dysplasia Institute.
Newborns wear either the small or extra-small sized sacks. Happiest Baby’s customer care
specialists are available seven days a week to help with any questions on size selection…or on
any other topic.