Originally set in New York City, I Love Lucy centers on Lucy Ricardo (Lucille Ball), and her singer/bandleader husband Ricky Ricardo (Desi Arnaz), along with their friends and landlords Fred Mertz (William Frawley) and Ethel Mertz (Vivian Vance). During the second season, Lucy and Ricky have a son named Little Ricky, whose birth was timed to coincide with Ball's real life delivery by Caesarean section.[4] "Little Ricky" literally grows up on the show and during the final season is played by 6-year-old actor Keith Thibodeaux.

Source: Wikipedia.org