Can there be a penis "to small"?

Rarely happens: Micropenis is something an occasional boy is born with. The doctor doing the newborn exam can tell the parents if a penis is tiny. If the penis is normal sized at birth, his growth hormone and testosterone keep his penis growing normally until adulthood. Be sure doctors look at the penis and testicles at check-ups. A smaller-than-average penis is normal, and not a micropenis, which is really tiny.

Only if: The penis is so small that it will not allow semen to be ejaculated into the vaginal vault for fertilization to occur.