Bristol Palin, the daughter of former Alaska Governor Sarah Palin who has spoken out in favor of sexual abstinence before marriage, is pregnant with her second child, she said in an contrite blog post.Palin made the announcement just over a month after her mother announced on Facebook that Bristol's planned May 23 marriage to Medal of Honor winner Dakota Meyer would not happen as scheduled."I wanted you guys to be the first to know that I am pregnant," Bristol Palin, 24, said on her blog on Thursday. "Honestly, I've been trying my hardest to keep my chin up on this one."Bristol Palin's first pregnancy as a teenager gained widespread attention in 2008 when it was announced during her mother's campaign as the Republican vice presidential nominee.At the time, Sarah Palin said that her daughter would marry the unborn baby's father, Levi Johnston, but the engagement was later called off.Bristol Palin, using her sometimes difficult experience as a teenage mother, has spoken out in favor of abstinence before marriage and is listed on the website of a booking agency as someone who can speak to issues of abstinence."Regardless of what I did personally, I just think that abstinence is the only ... 100 percent foolproof way to prevent pregnancy," Bristol Palin told ABC News program "Good Morning America" in 2009.In her announcement on her blog, Bristol Palin, who speaks often of her Christian faith, wrote that she does not want "any lectures" or sympathy about her latest pregnancy."I know this has been, and will be, a huge disappointment to my family, to my close friends and to many of you," she wrote.She did not identify the father of her unborn baby.