Tuesday, July 27, 2021
Home Feeds More twins are being born now than ever before: study

More twins are being born now than ever before: study


They found a 71% rise in twinning rates in North America, as well as significant rises in many European countries and in Asia

(Subscribe to Science For All, our weekly newsletter, where we aim to take the jargon out of science and put the fun in. Click here.)

More twins are being born now than ever before, largely due to rising use of in vitro fertilisation (IVF) and other assisted reproduction techniques, the first global study of human twinning has found.

With about 1.6 million twins born each year worldwide, the global twinning rate has risen by a third since the 1980s, to 12 per 1,000 deliveries from 9 per 1,000 around 30 years ago, the study found.

This might well be “peak twins”, scientists behind the research said — particularly in high-income regions such as Europe and North America where there is now an emphasis on refining fertility treatments to minimise multiple births.

“We think we’re actually at the peak,” said Christiaan Monden, a professor at Britain’s Oxford University who co-led the review. “This is likely to be an all-time high. The relative and absolute numbers of twins in the world are higher than they have ever been since the mid-twentieth century.”

Monden’s research team, whose findings were published on Friday in the journal Human Reproduction, analysed data on twinning rates for 165 countries between 2010 and 2015 and for 112 countries for the period 1980 to 1985.

They found a 71% rise in twinning rates in North America, as well as significant rises in many European countries and in Asia. For Asia overall, there was a 32% increase, they said, and only seven countries saw falls of more than 10% in twinning rates over the study period.

The researchers noted that rates of monozygotic or identical twins — born from the same egg — were barely changed, stable at about 4 per 1,000 deliveries worldwide.

This meant the vast majority of the increase in twinning rates was due to high numbers of dizygotic or non-identical twins — twins born from separate eggs.

This was especially true in Africa, Monden said, and is most likely to be due to genetic differences between African populations and other populations.

“Most twins you’ll meet in Japan are identical twins,” he said, “while most twins you’ll meet in Africa are non-identical – and we think that’s genetic.”

While factors such as women choosing to start families later, greater use of contraception, and lower fertility rates might be playing some part in the increase in twinning rates, Monden said medically assisted reproduction techniques — which began in the 1970s — are the main drivers.

Such fertility treatments were originally available in wealthier regions, but spread to emerging economies in Asia and Latin America in the 1980s and 1990s, reaching the relatively richer parts of South Asia and Africa after 2000.

You have reached your limit for free articles this month.

Subscription Benefits Include

Today’s Paper

Find mobile-friendly version of articles from the day’s newspaper in one easy-to-read list.

Unlimited Access

Enjoy reading as many articles as you wish without any limitations.

Personalised recommendations

A select list of articles that match your interests and tastes.

Faster pages

Move smoothly between articles as our pages load instantly.

Dashboard

A one-stop-shop for seeing the latest updates, and managing your preferences.

Briefing

We brief you on the latest and most important developments, three times a day.

Support Quality Journalism.

*Our Digital Subscription plans do not currently include the e-paper, crossword and print.



Source link

LEAVE A REPLY

Please enter your comment!
Please enter your name here

- Advertisment -

Most Popular

Recent Comments