If you really want to make babygros, go for it! As previous poster says, use a medium weight cotton jersey, a stretch stitch and get some KAM snaps (or non-branded ones) from eBay, with the pliers to attach them. HOWEVER...... babygrows are quite cheap to buy, often available nearly-new cheaper still, and a right fiddle as seen on the Sewing Bee. Maybe think about making items like joggers, hoodies, dresses, dungarees instead? I make for my granddaughter but focus on traditional dresses and tops with Peter Pan collars, pinafores and dungarees. I embroider or appliqué to make them unique. My daughter has a taste for Boden baby dresses, but not for their price tags.