Abstinence activist Bristol Palin gives birth to second child
Bristol Palin watches while her mother former Alaska governor Sarah Palin delivers her keynote speech at the Reagan 100 opening banquet at the Reagan Ranch Center in Santa Barbara, California on Feb. 4, 2011. (REUTERS/Mario Anzuoni)

Bristol Palin, a daughter of 2008 Republican vice presidential candidate Sarah Palin, has given birth to a second child out of wedlock.

Palin, 25, who has been an advocate of sexual abstinence before marriage, tweeted on Thursday that she had given birth to a girl, Sailor Grace. "My Heart Just Doubled," she wrote.

The father was not named. Palin announced she was pregnant in June, a few weeks after her engagement to Medal of Honor winner Dakota Meyer was called off.

Her first pregnancy as a teenager gained widespread attention in 2008 when it was disclosed during her mother's campaign as the running mate of Republican presidential nominee Senator John McCain.

Sarah Palin, a former Alaska governor, tweeted that the baby was born late on Wednesday. "Oh, perfect love! The best gift ever!" she wrote.

(Reporting by Ian Simpson; Editing by Leslie Adler)