USA Today reports that according to a report from the Centers for Disease Control and Prevention’s National Center for Health Statistics, “the number of twin births in the USA more than doubled from 1980 to 2009.”
In addition, “for mothers age 35 and over, those twin rates have skyrocketed. Among women 35-39, rates rose by nearly 100%, and among those 40 and over, rates rose more than 200%.”
Why the dramatic increase? According to CDC statistician Joyce Martin there are two reasons:
- About one-third of the increase over three decades was attributed to older maternal age and
- The other two-thirds likely the result of fertility-enhancing therapies – both drugs and technologies like in-vitro fertilization.