Despite the audience's reponse, Keys didn't miss a beat. The 29-year-old singer got right back on her feet and continued singing, although she finished out the song at a nearby piano.
Both Keys and her unborn baby were unharmed, according to the Huffington Post.
The 2010 Essence Music Festival began on Friday and lasted for three days with performances by Janet Jackson, Monica, Estelle, LL Cool J and Trey Songz.
The event was one of the Keys' last gigs beforeshe takes her unofficial maternity leave, reported E! Online.
Keys announced her pregnancy and engagement to fiancé Swizz Beatz in May.
