More twins are being born around the planet than ever, reports the scientific portal LiveScience. Since the 1980s, the twin birth rate in the world has increased by more than 30%: of nine births of Twins per 1,000 deliveries in 1980-1985, to 12 per 1,000 between 2010 and 2015. Furthermore, the absolute number of twin deliveries increased by 42% during this period: from 1.1 million in the early 1980s to 1.6 million in the early 2010s.
The natality in general you are feeling the influence of new coronavirus in the world. In rich countries, many couples are reluctant to start or expand a family. However, in the poorest places the twin births They are multiplying, according to a new study.
For comparison, the total number of births worldwide rose only 8% during the same period.
The medically assisted reproduction, which includes the in vitro fertilization (IVF) – that is, when an egg is fertilized with sperm in a lab dish and transferred to the uterus – can largely explain this increase, the authors said.
The gynecologist Tomás Hernández explain that the in vitro fertilization effectively increases the possibility of having twins, because more than one embryo is usually transferred to increase the chances that a birth will occur later.
Christiaan Monden, co-author of the study and professor of sociology at the University of Oxford in the United Kingdom, says that the relative and absolute numbers of Twins in the world they are higher than they have been since the middle of the 20th century, and they are likely to be an all-time high.
Another fact to take into account is that twin deliveries are associated with higher mortality rates among babies and children; also with more complications for mothers and their offspring during pregnancy, and during and after childbirth.
On the other hand, Hernández adds that women who have children at an older age are more likely to conceive twins.
The study researchers analyzed information about twin births of 165 countries between 2010 and 2015. Of 112 of these, the researchers also obtained information on those that occurred between 1980 and 1985, which allowed a comparison of these periods.
The scientists found that, during the three-decade stage, the rate of twins birth it increased by more than 10% in 74 of the 112 countries.
The rise is mainly due to more Twins, also known as dizygotic or fraternal twins. The number of monozygotic or identical twins has not varied around the globe, with around four births for every 1,000 deliveries.
At the continental level, North America experienced the largest increase in twin births, with an increase of 71% in the rate of births of this type during the period of three decades, followed by Europe, with a rise of 58%, and Oceania, with a 46% increase.
Hernández highlights that women, in Ecuador and in Latin America in general, still have children before the age of 30, so they do not usually require assisted treatments. This means that a large increase in twins is not registered in the country.
Africa has the highest twin rates in the world, with approximately 17 twin births per 1,000 deliveries. The rate was virtually unchanged over the three-decade study period. It is believed that some African populations they may be genetically more likely to have them, compared to other parts of the world.
But there is a big difference in the survival chances of the twins born in rich countries versus low-income nations.
In sub-Saharan Africa, in particular, many twins will lose their brother in their first year of life, between 200 and 300,000 each year, according to Jeroen Smits, a professor of comparative human development at Radboud University in the Netherlands and also a co-author of the study.
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