I'm 5'5", Pre-pregnancy 125lbs, and was 156lbs at term, had 9lb + baby, and the Small/medium fit well. I first wore this on day three post partum, and it was a kind of restricting and I was happy to take it off! However, by 1 week post partum it was much more comfortable and I've worn it almost everyday for the past month (I bought two to rotate through the wash). It becomes less and less restrictive as you shrink. While I'm still about 138lbs today, I'm wearing all my pre-pregnancy clothes again, and have been for several weeks. Comfortable enough to wear all day, but I never wanted to sleep in it.