They always tell you what to do in case you loose cabin pressure, but a baby being delivered I have not heard yet!
On a recent flight on China Air from Taiwan to Los Angeles, a pregnant passenger went into early labor. Fortunately, there was a physician from the University of California, Los Angeles, Dr. Angelica Zen, on board!
Dr. Zen was coming back from her honeymoon in Bali when flight attendants were asking for the assistance of any medical professionals. Even though this is not her expertise, she was willing to help ( speaking Mandarin Chinese helped so she could communicate with the mother).