试管婴儿有风险吗？

　　In the 24 years since the birth of Louise Brown，the world's first test－tube baby，thousands of would－be parents have been assure that as far as scientists knew there was no extra risk of genetic¹ damage associated with in－vitro fertilization，or IVF．No matter how sperm² meets egg--whether in a woman's body or in a Petri dish（and even if the sperm needs some help getting inside the egg）--nature is equally vigilant³ about preventing serious genetic mishaps⁴ from coming to term．With those assurances，test－tube births have soared from a few hundred a year in the early 1980s to tens of thousands today．治疗不孕损害婴儿的遗传基因吗？医生们过去认为不会有什么影响，现在他们对此不十分肯定了。
世界首例试管婴儿路易斯·布朗出生后２４年的时间里，成千上万想做父母亲的人们得到科学家们的保证说，试管内受精对基因不会有什么额外的危险。无论精子如何与卵子结合--是否在女人体内还是在较硬的试管壁上，（即使精子需外力帮助才与卵子结合），大自然都同样会阻止严重变形的基因分娩，有了这样的允诺和保证，试管婴儿的出生在20世纪80年代早期由每年的百余例上升到现如今的数万例。
But according to a pair of reports in last week's New England Journal of Medicine，that conventional wisdom may be wrong．In the first study，doctors in Britain and Australia found that infants conceived with both straightforward⁵ test－tube methods and a more invasive technique called intra－cytoplasmic sperm in jection，in which sperm is injected directly into the egg，have an 8.6% risk of major birth defects--including heart and kidney abnormalities，cleft palate and undescended testicles -- compared with the 4.2% rate in babies made the old－fashioned way．The second study，conducted by the U．S．Centers for Disease Control and Prevention（CDC），reported that babies conceived through what doctors call assisted reproductive technologies（ART）have 2.6 times the risk of low or very low birth weight --a significant risk factor for cardiac and cognitive⁶ problems．但上周的《新英格兰医学杂志》有两篇报告指出：这种传统的说法也许是错误的。在第一篇研究报告中，英国和澳大利亚的医生们发现，直接的试管受精和通过更具侵入性的技术--把精液通过注射直接与卵子相遇的方法而出生的婴儿，有8.6％存在着主要由出生造成的缺陷的危险性--包括心脏、肾功能不正常、裂腭、男孩隐睾症等。而正常受孕出生的孩子这种现象的比率只为4.2％。第二个研究报告是由"美国疾病控制与预防中心"主持作出的。报告指出，通过医生们所谓"协助生育技术"的方法而受孕出生的婴儿出生时低体重或严重低体重的危险是正常情况的2.6倍。这是引起心脏病和认知能力问题的危险因素。
There are plenty of reasons to take both studies seriously．In the low－birth－weight study，for example，the researchers allowed for the fact that parents who use assisted reproduction tend to be older than average and to have more multiple births--twins，triplets and so on．Even when they corrected for these factors，the disparity between babies conceived through ART and those conceived normally remained．我们有充足的理由对以上两种研究严肃对待。例如：有关低体重出生研究方面，研究者们已然考虑到这样的事实，即那些想通过医学手段而受精生育的夫妻们年龄比一般生育年龄大些，而且一次多胎--双胞胎、三胞胎等等。即使他们避免了这些因素，但是通过"协助生育技术"生育的婴儿与正常生育的婴儿之间仍然存在差异。
But there's no need to panic．Independent experts are quick to point out that the reports are hardly definitive⁷．Couples who seek reproductive help are not just older；they are also--though it may seem like stating the obvious--infertile．"You're comparing two different groups of patients here，"says Dr．William Schoolcraft，director of the Colorado Center for Reproductive Medicine．"You have women with the disease of infertility⁸，and you're comparing them with women who don't have the disease．"Some of the same caveats⁹ apply to the birth－defects study，say experts．Here，too，earlier research had found no significant differences between test－tube babies and convention－ally conceived kids．And here，again，the new study didn't correct for the fact that women who get reproductive assistance often have something wrong with their reproductive system in the first place．但也没有必要过分恐慌。其他专家们迅速指出这些报道绝不是确定性的。寻求生育帮助的夫妇并不仅仅是年龄偏大的，他们也是明显的不育夫妇。"科罗拉多生育医学研究中心"负责人威廉姆·斯库克拉夫特博士说："你们是把两类不同的病人进行对比。你们这儿有的是些患有不孕疾病的妇女，而你们却把她们与那些根本没有不孕症的妇女进行对比"。
专家们说，一些同样的防止误解的说明适用于出生缺陷研究。在这里，较早期的研究发现：试管婴儿与正常婴儿没有重大的区别，而且新研究并没有纠正这样的事实，即寻求医学手段而受孕的妇女首先她们本身的生育系统有问题。
Even if these new studies are borne out by later research--already under way in infertility programs in Australia and the U．S．--the risks to kids conceived by assisted reproduction remain reassuringly¹⁰ small．And even if the danger is twice what doctors previously¹¹ believed，91% of ART babies would still be born perfectly¹² healthy．Says Dr．Zev Rosenwaks，director of New York Presbyterian Hospital's infertility program："If you ask a couple if they would rather not have a child at all or try to have a child that over 90% of the time will be normal，I think they will choose to have the child．"即使这些新研究被后期的研究所证实--在澳大利亚和美国有关不孕项目的研究已经在进行，通过医学受精生育的孩子的出生会有缺陷危险仍然肯定是极小的。即使这种危险是医生们先前相信的两倍，但91％这类出生的婴儿仍然完全健康。纽约基督教长老会医院妇女不孕科主任--兹夫·罗森瓦克斯博士说："如果你问一对夫妇她们愿意一生不要孩子，还是愿意生育一个孩子，而且有多于90％的可能孩子是正常的，我想他们肯定会选择要孩子。"

1 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

2 sperm   

n.精子，精液

参考例句：

• Only one sperm fertilises an egg.只有一个精子使卵子受精。
• In human reproduction,one female egg is usually fertilized by one sperm.在人体生殖过程中，一个精子使一个卵子受精。

3 vigilant   

adj.警觉的，警戒的，警惕的

参考例句：

• He has to learn how to remain vigilant through these long nights.他得学会如何在这漫长的黑夜里保持警觉。
• The dog kept a vigilant guard over the house.这只狗警醒地守护着这所房屋。

4 mishaps   

n.轻微的事故，小的意外( mishap的名词复数 )

参考例句：

• a series of mishaps 一连串的倒霉事
• In spite of one or two minor mishaps everything was going swimmingly. 尽管遇到了一两件小小的不幸，一切都进行得很顺利。 来自《现代汉英综合大词典》

5 straightforward   

adj.正直的，坦率的；易懂的，简单的

参考例句：

• A straightforward talk is better than a flowery speech.巧言不如直说。
• I must insist on your giving me a straightforward answer.我一定要你给我一个直截了当的回答。

6 cognitive   

adj.认知的，认识的，有感知的

参考例句：

• As children grow older,their cognitive processes become sharper.孩子们越长越大，他们的认知过程变得更为敏锐。
• The cognitive psychologist is like the tinker who wants to know how a clock works.认知心理学者倒很像一个需要通晓钟表如何运转的钟表修理匠。

7 definitive   

adj.确切的，权威性的；最后的，决定性的

参考例句：

• This book is the definitive guide to world cuisine.这本书是世界美食的权威指南。
• No one has come up with a definitive answer as to why this should be so.至于为什么该这样，还没有人给出明确的答复。

8 infertility   

n.不肥沃，不毛；不育

参考例句：

• It is the Geneva, Switzerland-based Biotech Company's second recombinant infertility drug. 它是瑞士生物技术公司在日内瓦的公司生产的第二种重组治疗不孕症的药。 来自英汉非文学 - 生命科学 - 生物技术制药疫苗
• Endometritis is a cause of infertility. 子宫内膜炎是不育的原子。 来自辞典例句

9 caveats   

警告

参考例句：

• I would offer a caveat for those who want to join me in the dual calling. 为防止发生误解，我想对那些想要步我后尘的人提出警告。 来自辞典例句
• As I have written before, that's quite a caveat. 正如我以前所写，那确实是个警告。 来自互联网

10 reassuringly   

ad.安心，可靠

参考例句：

• He patted her knee reassuringly. 他轻拍她的膝盖让她放心。
• The doctor smiled reassuringly. 医生笑了笑，让人心里很踏实。

11 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

12 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。