Well you have to wear a sports bra all the time for the first 4-6 weeks. So pockets (space for the implants) heal where they are supposed to heal. When you sleep on your side or stomach, you're actually changing the shape of the pocket and of course healing is happening when we're sleeping. It's not really a life or death issue but they prefer you sleep on your back for the first week to get the pocket in that perfect position.
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