Fertility treatments like in vitro fertilization led the twin birthrate to rise from the early '80s. Now the rate has started to decline among white women. JGI/Jamie Grill/Getty Images hide caption toggle caption JGI/Jamie Grill/Getty Images Shots - Health News Twin Birthrate Drops For First Time Since The '80s October 3, 2019 The twin birthrate nearly doubled between 1980 and 2014. Now it's going down among white mothers. What's behind the change?