How many twins are born each year?

The birth rate of twins in the United States was one out of every 30 live births as of a study performed in 2009. This means the average number of twins being born each year is more than 130,000.

Research suggests the dramatic increase in the number of twin births is due to the increased use of fertility drugs and assisted reproduction, which accounts for about two-thirds of the increase in twin births. The remaining third seems to be caused by the increase in the average age of a mother at birth, since older women are more likely to produce more than one egg each cycle.