In 2005, 133,122 twin babies and 6,208 triplet babies were born in the United States. In 1980, there were only 69,339 twin and 1,337 triplet births. Why the increase? For one, more women are having babies after age 30. Women in their 30s are more likely than younger women to conceive more than one baby naturally. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.