Is it normal that my 17-week-old baby hasn't done the "push-up" during tummy time?
By 4 months of age a child should be pushing up and starting to working towards rolling over. Rolling up a towel into the shape of a pool noodle and putting it below your baby's armpits to support the chest can help encourage him to start using upper body to push up. Do this for a few minutes several times a day -- keep your child on his stomach and lie next to him while providing entertainment with facial expressions or toys. Work towards longer periods of tummy time each day, but pick your child up only when he starts to get frusterated or upset. If things do not seem to be improving with your efforts, a trip to the pediatrician may be warranted.