A study conducted by Oxford University has found that more twins are being born in the world than ever before. A total of 1.6 million twins are delivered each year, with the twin birth rate increasing by a third over the past 40 years. One in every 43 babies born now is part of a set of twins.
The study was also conducted with the help of the French Museum of Natural History and Radboud University in the Netherlands. Researchers analyzed the rate of twin births between the years 2010-2015 in 165 countries, which comprise 99% of the global population. They also assembled data on the rate of twins delivered between 1980-1985 in 112 countries. In 75% of those 112 countries, 10% more twins had been born than was the norm in previous years.
Attitudes towards twin births had shifted in the 1990s as doctors started to question the health problems associated with multiple births. Many fertility practices were modified in that era, some restricting the number of embryos that could be transferred through in-vitro fertilization.
Analysis of 40 years of data finds twins births at all time high globally
Professor Christiaan Monden, the lead author of the study, who works at the Leverhulme Centre of Demographic Science, explained that the incline in twin births is due to fertility treatments in tandem with deferred childbearing.
“The number of twins on Earth is now at a record high. Women are having children later and fertility treatment is becoming more widespread and popular. And because age and MAR (medically assisted techniques) such as IVF and ovulation stimulation are linked with higher numbers of multiple births, these comparatively older mothers are then more likely to have twins,” said Monden.
He insists that “This is important because twin deliveries are associated with higher child mortality and complications for the mother during pregnancy and delivery.”
The study found that Africa has the highest occurrence of twin births out of every region studied, with Asia close behind: 80% of all twins are now born in those two continents. But researchers also saw huge increases in twins in most European countries as well as in North America.
Monden said “‘Our study reveals remarkable changes in the global twinning landscape in past decades. This huge increase has been driven mainly by more women using fertility treatments. This trend started in the world’s wealthier regions in the 1970s, spread to emerging economies in Asia and Latin America in the 1980s and 90s, and reached more prosperous populations in South Asia and Africa from 2000.”
Monden hopes that the study will contribute to further healthy deliveries of twins around the world, “accurately forecasting the healthcare needs of twins and their mothers depends on having accurate data showing how many twins are being born.
“We hope our research adds further to understanding about what is required to provide this care across the globe.”