Record international number of twin births

The rise in the rate of twins in the U.S. coincided with the introduction and wide adoption of fertility treatments, like in vitro fertilization, and drugs that induce ovulation. When the first baby in the U.S. was conceived with assisted reproductive technology in 1981, twins accounted for roughly one out of every 53 births. By 2014, twins had become nearly twice as common, at one out of every 29 births.