Claudette Kibble -- Houston, 1986-90

Kibble killed three of her five babies over a four-year period. She claimed each child had died of natural causes but confessed in 1995 to drowning two, suffocating one and attempting to suffocate a fourth child. A psychiatric defense never materialized, and at age 23 Kibble pleaded guilty in exchange for a life sentence.

http://www.chron.com/cs/CDA/story.hts/special/drownings/957431
http://members.tripod.com/~leelah/index24.html