After three decades of increases, the US birth rate for twins has dropped. The steady rise had been attributable largely to the use of in vitro fertilization. Now, the 4% drop from 2014 to 2018 could be attributable to new reproductive technology that makes single births more likely, a report from the Centers for Disease Control and Prevention says. Multiple births are riskier for the mother and babies, the Wall Street Journal reports, so researchers see the decline as a positive. "In the media, there are often stories about very cute twins," a CDC researcher said, per NBC. "These stories don’t focus on the risk." The risks for the mother include diabetes, high blood pressure, hemorrhaging, and postpartum depression. There's also a higher risk of death for both moms and babies, and twins are more likely to be born sooner and smaller.
The number of twin births more than doubled from 68,339 in the 1980s to a peak of 138,961 in 2007, then fell to 123,536 in 2018, the National Center for Health Statistics found. Until recently, many fertility doctors transferred multiple embryos during in vitro fertilization in hopes that at least one would be successful. Often, that led to multiple births. Now, per the Washington Post, many doctors transfer one embryo at a time. Advances in embryo freezing and genetic testing have helped make single transfers successful more often. "I am elated," a Texas specialist said. "What I take away from this is that we’re working hard to ensure that families have the healthiest pregnancies possible." (Read more twins stories.)