I own 4 of these diaper cover which I pair with a prefold and fleece liner . I do not personally use these for night time diapering - I use 2 prefold with a homemade wool cover . my 6 month old , 15 pound daughter wear a medium size cover which have ton of grow room - which be how I want to buy it so we would get multiple month of use out of these cover . I really can not say enough good thing about these cover . we have not ever have a leak with they ! they also contain poop very well . great cover , great price , great performance !