Stork Alert! Billy Joel & Wife Alexis Welcome Baby Girl — Find Out All The Details

It's a girl! Billy Joel and his wife, Alexis Joel, are celebrating the arrival of their daughter, Della Rose Joel.

The newborn weighed in at 7 lbs, 6.5 oz., when she was born on Aug.12 at 2:40 a.m.

RadarOnline.com was first to report in April that Billy, 66, and 33-year-old Alexis were expecting a child together.

Though Alexis, a former financial advisor for the investment bank Morgan Stanley, showed off her growing belly in private family photos, she kept a low profile whenever she was in public to keep her pregnancy a secret.

"She doesn't leave the house too often because she doesn¹t want anyone to know," a source told RadarOnline.com last spring. "And she wears big dresses to cover it up."

Billy and Alexis tied the knot in a surprise July 4 ceremony at their Long Island estate.