The twinning rate has increased in thirty years, from 9.1 twin births per 1000 total births in the 1980s to 12 per 1000 in the 2010s.
- Eight out of ten twins are born in Africa or Asia.
- Only the rate of dizygotic twinning (pregnancies of “fraternal twins”) varies from one country or from one period to another.
There have never been so many twin births in the world, according to a new study published in the journal Human Reproduction. Two factors explain this increase:a diffusion of medically assisted procreation (MAP), which is associated with a high risk of multiple births; Ie delay in childbearing, the probability of a twin pregnancy increasing with the age of the women.
The twinning rate has increased in thirty years, from 9.1 twin births per 1000 total births in the 1980s to 12 in the 2010s. More than 1.6 million pairs of twins are born every year in the world, that is 3.2 million twin children; nearly one in 40 babies is a twin.
“A public health problem”
The three authors of the study, Gilles Pison, from the National Museum of Natural History and the National Institute for Demographic Studies, Christiaan Monden, from the University of Oxford, and Jeroen Smits, from Radboud University in Netherlands, have used all the available data to estimate the twinning rate in the different countries of the world and describe the changes that have occurred over three decades.
“This “boom twin” poses a public health problem, because they are fragile children who require more care and have a higher mortality than the others, not to mention the difficulties for the parents to take care of two babies at the same time”, underline the experts in a press release. They continue: “As a result, governments and medical colleges have been trying for several years to change medical practices so that ART results in single rather than multiple pregnancies.”
The increase in births only concerns fraternal twins
Of the 3.2 million twins born each year:
– 1.3 million are born in Africa (i.e. 650,000 pairs).
– 1.3 million in Asia (i.e. 650,000 pairs).
– About 600,000 twin children appear in other continents (i.e. 300,000 pairs).
Eight out of ten twins are therefore born in Africa or Asia. It should be noted that only the dizygotic twinning rate (pregnancies of “fake twins”) varies from one country or period to another. Monozygotic twins (the “identical twins”) are born everywhere in the same proportions, without this having changed: out of 1000 pregnancies, four are identical twins. “The increase in the frequency of twins globally is therefore solely due to the unprecedented rise in pregnancies of dizygotic twins,” conclude the researchers.
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