母乳喂养让儿童更聪明

 A new study provides some of the best evidence to date that breast-feeding can make children smarter, an international team of researchers said on Monday.

Children whose mothers breast-fed them longer and did not mix in baby formula scored higher on intelligence tests, the researchers in Canada and Belarus reported.

About half the 14,000 babies were randomly¹ assigned to a group in which prolonged and exclusive breast-feeding by the mother was encouraged at Belarussian hospitals and clinics. The mothers of the other babies received no special encouragement.

Those in the breast-feeding encouragement group were, on average, breast-fed longer than the others and were less likely to have been given formula in a bottle.

At 3 months, 73 percent of the babies in the breast-feeding encouragement group were breast-fed, compared to 60 percent of the other group. At 6 months, it was 50 percent versus² 36 percent.

In addition, the group given encouragement was far more likely to give their children only breast milk. The rate was seven times higher, for example, at 3 months.

The children were monitored for about six and a half years.

The children in the group where breast-feeding was encouraged scored about 5 percent higher in IQ tests and did better academically, the researchers found.

Previous studies had indicated brain development and intelligence benefits for breast-fed children.

But researchers have sought to determine whether it was the breast-feeding that did it, or that mothers who prefer to breast-feed their babies may differ from those who do not.

The design of the study - randomly assigning babies to two groups regardless of the mothers' characteristics - was intended to eliminate the confusion.

"Mothers who breast-feed or those who breast-feed longer or most exclusively are different from the mothers who don't," Michael Kramer of McGill University in Montreal and the Montreal Children's Hospital said.

"They tend to be smarter. They tend to be more invested in their babies. They tend to interact with them more closely. They may be the kind of mothers who read to their kids more, who spend more time with their kids, who play with them more," added Kramer, who led the study published in the journal Archives of General Psychiatry³.

The researchers measured the differences between the two groups using IQ tests administered by the children's pediatricians and by ratings by their teachers of their school performance in reading, writing, math and other subjects.

Both sets of scores were significantly higher in the children from the breast-feeding promotion⁴ group.

The study was launched in the mid-1990s. Kramer said the initial idea was to do it in the United States and Canada, but many hospitals in those countries by that time had begun strongly encouraging breast-feeding as a matter of routine.

The situation was different in Belarus at the time, he said, with less routine encouragement for the practice.

Kramer said how breast-feeding may make children more intelligent is unclear.

"It could even be that because breast-feeding takes longer, the mother is interacting more with the baby, talking with the baby, soothing⁵ the baby," he said. "It could be an emotional thing. It could be a physical thing. Or it could be a hormone⁶ or something else in the milk that's absorbed by the baby".

Previous studies have shown babies whose mothers breast-fed them enjoy many health advantages over formula-fed babies.

These include fewer ear, stomach or intestinal⁷ infections, digestive problems, skin diseases and allergies⁸, and less risk of developing high blood pressure, diabetes⁹ and obesity¹⁰.

The American Academy of Pediatrics recommends that women who do not have health problems exclusively breast-feed their infants for at least the first six months, continuing at least through the first year as other foods are introduced.

1 randomly   

adv.随便地，未加计划地

参考例句：

• Within the hot gas chamber, molecules are moving randomly in all directions. 在灼热的气体燃烧室内，分子在各个方向上作无规运动。 来自辞典例句
• Transformed cells are loosely attached, rounded and randomly oriented. 转化细胞则不大贴壁、圆缩并呈杂乱分布。 来自辞典例句

2 versus   

prep.以…为对手，对；与…相比之下

参考例句：

• The big match tonight is England versus Spain.今晚的大赛是英格兰对西班牙。
• The most exciting game was Harvard versus Yale.最富紧张刺激的球赛是哈佛队对耶鲁队。

3 psychiatry   

n.精神病学，精神病疗法

参考例句：

• The study appeared in the Amercian science Journal of Psychiatry.这个研究发表在美国精神病学的杂志上。
• A physician is someone who specializes in psychiatry.精神病专家是专门从事精神病治疗的人。

4 promotion   

n.提升，晋级；促销，宣传

参考例句：

• The teacher conferred with the principal about Dick's promotion.教师与校长商谈了迪克的升级问题。
• The clerk was given a promotion and an increase in salary.那个职员升了级，加了薪。

5 soothing   

adj.慰藉的；使人宽心的；镇静的

参考例句：

• Put on some nice soothing music.播放一些柔和舒缓的音乐。
• His casual, relaxed manner was very soothing.他随意而放松的举动让人很快便平静下来。

6 hormone   

n.荷尔蒙，激素，内分泌

参考例句：

• Hormone implants are used as growth boosters.激素植入物被用作生长辅助剂。
• This hormone interacts closely with other hormones in the body.这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。

7 intestinal   

adj.肠的；肠壁；肠道细菌

参考例句：

• A few other conditions are in high intestinal obstruction. 其它少数情况是高位肠梗阻。 来自辞典例句
• This complication has occasionally occurred following the use of intestinal antiseptics. 这种并发症偶而发生在使用肠道抗菌剂上。 来自辞典例句

8 allergies   

n.[医]过敏症；[口]厌恶，反感；（对食物、花粉、虫咬等的）过敏症( allergy的名词复数 )；变态反应，变应性

参考例句：

• Food allergies can result in an enormous variety of different symptoms. 食物过敏会引发很多不同的症状。 来自辞典例句
• Let us, however, examine one of the most common allergies; hayfever. 现在让我们来看看最常见的变态反应的一种--枯草热。 来自辞典例句

9 diabetes   

n.糖尿病

参考例句：

• In case of diabetes, physicians advise against the use of sugar.对于糖尿病患者，医生告诫他们不要吃糖。
• Diabetes is caused by a fault in the insulin production of the body.糖尿病是由体內胰岛素分泌失调引起的。

10 obesity   

n.肥胖，肥大

参考例句：

• One effect of overeating may be obesity.吃得过多能导致肥胖。
• Sugar and fat can more easily lead to obesity than some other foods.糖和脂肪比其他食物更容易导致肥胖。