While it doesn't have a waist strap, it does feature a one pull adjuster on its back, so you can reach around and adjust it easily to get a snug fit. (wetheparents.org)
This new generation baby carrier has the waist belt that helps to support the lower lumbar region in adults and also allows for back and outward facing carrying. (babycarrierhq.com)
I carry pretty small in the belly so I did have the waist taken in a little bit, as I wanted the dress to be a bit more fitted to my belly.. (tiffanyrose.com)