By: Geoffrey Kalazar
Fewer twins are being born to parents in the United States, according to recent research.
A report release last week indicates that the twin birthrate in the U.S., which rose for many years, has begun to reverse itself.
“One theory researchers have put forward to explain the change is that fertility therapies that previously involved transfers of multiple embryos are less common,” the New York Times reported.
According to The National Center for Health Statistics, “following years of relative stability, twin births began to climb in the United States in the early 1980s, rising 79% from 1980 to 2014. In 1980, one in every 53 births was a twin, compared with one in every 29 births in 2014. The increase in twinning over the more than three decades was widespread, occurring across age and race and Hispanic-origin groups, and in all U.S. states. It is important to track twin birth rates as twins are at greater risk than singletons for poor outcomes, including preterm birth and neonatal morbidity and mortality. This report presents trends in twin childbearing overall for 1980–2018, and by mate.
Among the National Vital Statistics System’s key findings:
Following more than three decades of increases, the twin birth rate declined 4% during 2014–2018, to the lowest rate in more than a decade, 32.6 twins per 1,000 total births in 2018.
The number of births in twin deliveries declined an average of 2% per year from 2014 through 2018, dropping to 123,536 births in 2018.
Twin birth rates declined among mothers aged 30 and over, with the largest declines among older mothers aged 40 and over.
The twinning rate dropped 7% among non-Hispanic white mothers from 2014 to 2018 (34.3 in 2018), but was essentially unchanged among non-Hispanic black (40.5) and Hispanic (24.4) mothers.
Twin birth rates declined in 17 states and rose in three states.
Twinning declined among non-Hispanic white mothers, but was essentially stable for non-Hispanic black and Hispanic mothers, the report noted.
The twin birth rate fell 7% among births to non-Hispanic white women, from 36.7 per 1,000 births, to 34.3 from 2014 to 2018.
Twinning among non-Hispanic black (40.0 in 2014 to 40.5 in 2018) and Hispanic mothers was essentially the same between the two time periods.
Non-Hispanic black mothers were most likely to have a twin births.