1,433. The Eight Upper Signs
Hilchos Ishus 2:6
The signs of infertility are that the woman in question: doesn’t grow breasts; stiffens during marital relations; her abdomen does not look like that of a woman; her voice is as deep as a man’s. A naarah, a bogeres and an ailonis are each considered an adult.
Hilchos Ishus 2:7
A woman has eight upper signs of maturity, as follows: when she stretches her hand back, a crease forms in her breast; her areolas darken; placing a hand on the end of the breast would make a depression before rising; creases form at the end of the breast and the nipple takes shape – the Rambam notes that his teachers maintained that the creases forming is sufficient; the breasts protrude; they become erect; the mons pubis forms between the stomach and the genitals, the flesh of this mound becomes soft.