How long before infant has a bowel movement without struggling?

It depends: The problem is that babies aren't coordinated and don't open their sphincter immediately when they have a bowel movement. Also, it's harder to have a bowel movement when you are lying down. As long as the stool is soft, there really isn't a problem with them straining a bit. It doesn't necessarily mean that there is anything wrong. If the stool is hard balls, see your doctor for help.

Infant BM's: Infants may grunt during a bowel movement but struggling or appears uncomfortable is not normal. If the stools are formed in the diaper this may be constipation. If this is the case, in the first 2 months try a tsp. of dark Karo syrup in 2 oz. warm water 2x per day. If 2 to 4 months try 2 oz of apple juice twice a day. If older and eating solids, increase fruits and juice until stools come easy.