Assessment and care and major problems of the newborn practice

At a six-week check, the mother of a healthy term baby says he brings up milk after most feeds and seems more settled when he is not flat on his back. Her own mother has told her to lay him on his side, and a friend has lent her a foam positioning wedge. He is thriving, feeds happily, has no cough and no distress with feeds. Which one of the following is the most appropriate sleeping advice?