Camille Allen is making babies out of professional sculpture's clay. Here she tells how she does that (read more on her website).
I use various kinds of professional doll sculptors' clay to make the babies. The babies have soft English mohair to imitate fine baby hair and are blushed with paints for realism to enhance their tiny wrinkles and creases.
Starting from detailed photographs and a lump of clay, sculpting a lifesize or miniature baby begins. It takes many, many hours of patient concentration to form a realistic baby and finish with fine details - including wrinkles and fingernails.
She also makes babies in natural, life size. They are also for sale. You can see more of her work on her online gallery.