Bristol is already the mother to 6-year-old Tripp, who she shares with her ex Levi Johnston. Bristol recently called off her engagement to Medal of Honor recipient Dakota Meyer amid tabloid rumors in May that Dakota had a "secret wife."
The 24-year-old daughter of former Alaska Governor Sarah Palin announced that she was expecting in a blog post in June that some criticized for having what sounded like a negative tone.
"I wanted you guys to be the first to know that I am pregnant," Bristol wrote on the June 25 blog post, adding, "I know this has been, and will be, a huge disappointment to my family, to my close friends, and to many of you."
Bristol later clarified her remarks in another post, stressing, "I do not regret this baby. This baby is not a disappointment, and I cannot wait to be a mom times two. Tripp is going to make the best big brother!!"