The researchers collected information on twinning rates from 165 countries for 2010 to 2015, and compared them with rates for 1980 to 1985. The number of twins born perthousand deliveries is now particularly high in Europe and North America - and worldwide it's gone from nine per 1,000 deliveries to 12. But twin rates in Africa have always been high and haven't changed much over the past 30 years, which could be due to population growth.

研究人员收集了2010年至2015年来自165个国家的双胞胎比率信息，并将其与1980年至1985年的进行了比较。欧洲和北美每一千个新生儿中的双胞胎比率特别高---全世界的双胞胎出生率已从 每1000个中有9个增长至了12个。但是非洲的双胎率一直很高，并且在过去30年中变化不大，这可能是由于人口增长所致。

Helping hand

伸出援助之手

Africa and Asia make up about 80% of all twin deliveries in the world at present. Prof Christiaan Monden, the study's author from the University of Oxford, said there was a reason for that.

目前，非洲和亚洲双胞胎出生率约占全球的80%。牛津大学研究报告的作者克里斯蒂安·蒙登（Christiaan Monden）教授说，这是有原因的。

The twinning rate in Africa is so high because of the high number of dizygotic twins - twins born from two separate eggs - born there," he said." This is most likely to be due to genetic differences between the African population and other populations.

他说：“非洲的双胞胎率如此之高，是因为那里有大量异卵双胞胎，即由两个卵子生下来的双胞胎。”这很可能是由于非洲人口与其他人口之间的遗传学差异造成的。

"Twinning rates in Europe, North America and Oceanic countries have been catching up - and the increasing use of medically assisted reproduction since the 1970s - for example IVF, ICSI, artificial insemination and ovarian stimulation - have been the main reason.

“欧洲，北美和大洋洲国家的双胞胎出生率也一直在攀升，主要原因是自1970年代以来该地区越来越多地使用医学辅助生殖-例如IVF（试管婴儿），ICSI（第二代试管婴儿），人工授精和促排卵。

These techniques all increase the likelihood of a multiple birth. Women choosing to start families later in life, increased use of contraception and lower fertility overall also play a role, the review says.

这些技术都增加了多生的可能性。该评论说，原因在于女性选择晚婚，更多地使用避孕药具和生育能力降低也有一定的原因。

But the emphasis is now on singleton pregnancies, which are safer, says Prof Monden. "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," he says. Twins have more complications at birth, are more often born premature and have lower birth weights and higher still birth rates.

蒙登教授说，但是现在的重点是更安全的单胎妊娠。 他说：“这很重要，因为双胞胎分娩会增加婴儿和儿童的死亡率，并增加婴儿和孕妇孕期，和分娩中和分娩后的并发症。”双胞胎出生时的并发症更多，很多双胞胎早产，体重不足，死胎率也高。

Survival chances

存活几率

The review found that the fate of twins in low and middle-income countries was more of a concern. In sub-Saharan Africa, in particular, many twins will lose their co-twin in their first year of life - more than 200,000 each year." While twinning rates in many rich Western countries are now getting close to those in sub-Saharan Africa, there is a huge difference in the survival chances," said Prof Jeroen Smits, a study author.

评论发现，中低收入国家的双胞胎命运更加令人担忧。特别是在撒哈拉以南的非洲，许多双胞胎在出生后的第一年就会失去孪生的兄弟姐妹，每年数量超过200,000。”虽然许多富裕的西方国家的孪生率现在已经接近撒哈拉以南非洲的孪生率。 但是婴儿存活几率却有很大差异。”研究作者Jeroen Smits教授说。

Looking ahead, the researchers say India and China will play a major role in future twinning rates. Declining fertility, older mothers at birth and techniques like IVF will all have a bearing on the numbers of twins in years to come.

研究人员说，展望未来，印度和中国将在未来的双胞胎出生率中占有重要的比重。生育力下降，大龄母亲以及IVF（试管婴儿）等技术都将对未来几年的双胞胎数量产生影响。返回搜狐，查看更多