2014年经济学人 多胞胎 多胞胎怀孕率的减少是件好事

Multiple births

Oh, baby

A reduction in multiple-birth pregnancies¹ is a good thing

IT HAS long been known that in-vitro fertilisation (IVF) increases the chances of multiple births, as several fertilised eggs are implanted in a woman to improve the chances of pregnancy².

A fifth of all successful IVF treatments in Britain result in multiple-birth pregnancies, compared with just over 1% from natural conceptions.

Such was the success of IVF after the first test-tube baby was born in 1978 that the rate of all multiple-birth pregnancies rose from ten per 1,000 in that year to 16.4 in 2009.

The total number of multiple births doubled during that time. However, for women over 35—frequently users of IVF—it shot up 600%.

When all goes well, a multiple birth can be good news for women who had difficulty conceiving.

But it also carries risks: the infant mortality rate is five times higher than for single births.

So the fact that newly released statistics show that the number of multiple births has started to fall is welcome.

This is largely a result of a new policy adopted by the Human Fertilisation and Embryology Authority (HFEA), a regulator.

In 2009 it launched the elective single-embryo transfer policy (now part of its multiple-births minimisation strategy) with the aim of reducing overall IVF multiple pregnancies from 27% in 2008 to 20% initially³.

HFEA’s latest figures, dating from 2012, show that the rate has slowed to 18%. The current target is 10%.

According to the HFEA, multiple-birth pregnancies carry a higher risk of premature⁴ delivery and children having disabilities as well as late miscarriage⁵, high blood pressure and pre-eclampsia for expectant mothers.

At least that risk is now being tackled for IVF users.

1 pregnancies   

怀孕，妊娠( pregnancy的名词复数 )

参考例句：

• Since the wartime population needed replenishment, pregnancies were a good sign. 最后一桩倒不失为好现象，战时人口正该补充。
• She's had three pregnancies in four years. 她在四年中怀孕叁次。

2 pregnancy   

n.怀孕，怀孕期

参考例句：

• Early pregnancy is often accompanied by nausea.怀孕早期常有恶心的现象。
• Smoking during pregnancy increases the risk of miscarriage.怀孕期吸烟会增加流产的危险。

3 initially   

adv.最初，开始

参考例句：

• The ban was initially opposed by the US.这一禁令首先遭到美国的反对。
• Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。

4 premature   

adj.比预期时间早的；不成熟的，仓促的

参考例句：

• It is yet premature to predict the possible outcome of the dialogue.预言这次对话可能有什么结果为时尚早。
• The premature baby is doing well.那个早产的婴儿很健康。

5 miscarriage   

n.失败，未达到预期的结果；流产

参考例句：

• The miscarriage of our plans was a great blow.计划的失败给我们以巨大的打击。
• Women who smoke are more to have a miscarriage.女性吸烟者更容易流产。