Baby Sims Can Display Feet and Hands by Quizicalgin

From quizicalgin.tumblr: The Sleeper Footies for your baby sims. Now your sim babies can wiggle about and look adorable. There are two sets, one for girls and one for boys. Both have one preset and have two recolorable channels. This is not a default replacement. You can switch to these by putting them into CAS via Master Controller/Stylist.

You can download this mod here.