The relative and absolute numbers of twins in the world are higher than they have ever been since the mid-twentieth century and this is likely to be an all-time high”.
A study led by experts at the University of Oxford found that about 1.6 million sets of twins are born every year.
The all-time rate of double births stems from more women waiting to have children until they are older, while also having better access to medically assisted reproduction procedures, in vitro fertilization (IVF), ovarian stimulation, and artificial insemination, the researchers say in a study published Friday in the journal Human Reproduction.
The researchers believer, however, that the twins’ peak won’t last, particularly in Europe and North America, as there is now a focus on achieving single births.“The relative and absolute numbers of twins in the world are higher than they have ever been since the mid-twentieth century and this is likely to be an all-time high,” Professor Christiaan Monden, the lead author at the University of Oxford, said. “This is important as twin deliveries are associated with higher death rates among babies and children and more complications for mothers and children during pregnancy, and during and after delivery.”
Monden and colleagues from universities in France and the Netherlands collected data on double births between 2010 and 2015 from 165 countries, representing 99 percent of the world’s population. For 112 countries, they were able to examine data covering 1980 to 1985.
Monden said about 80 percent of all twin deliveries in the world now take place in Asia and Africa. The absolute number of twin deliveries has increased everywhere except in South America. In Africa this increase is almost entirely caused by population growth.For 74 percent of the 112 countries for which data were available for both periods, the increase was more than 10 percent. In North America, the increase was 71 percent, and 32 percent in Asia.