Infertility was the inability for a lifeform to produce offspring.
Peri Brown was left infertile after contracting Spectrox toxaemia. (TV: The Caves of Androzani, AUDIO: The Widow's Assassin)
Lord Haldoran attempted multiple times to impregnate his wife Donna before discovering that she was infertile, leading to their divorce. (PROSE: Legacy of the Daleks)
Claire couldn't bear children by the time of 24 December 2002, even after trying IVF treatment, but later, in January (TV: Night Terrors) or on 11 February 2003, (PROSE: Night Terrors) a Tenza later named George assimilated into the "nest" of Claire and her husband, Alex, using an innate psychic field and a perception filter, cloaking the events of George's "birth". (TV: Night Terrors)
Amy Pond was rendered infertile after her ordeal at Demons Run, after the birth of her first child, River Song. (TV: A Good Man Goes to War) This put great strain on her marriage to Rory Williams for a short time, (TV: Asylum of the Daleks) and culminated in divorce. (WC: Pond Life) They later reconciled while on a trip to the Dalek Asylum with the Eleventh Doctor. (TV: Asylum of the Daleks) The couple later adopted a son, Anthony Williams. (WC: P.S., Rory's Story, PROSE: About the Authors)