Do infertility treatments damage babies'genes? Doctors used to think not．Now they are not so sure．
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 genetic damage associated with in－vitro fertilization，or IVF．No matter how sperm 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 vigilant about preventing serious genetic mishaps 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．
治療不孕損害嬰兒的遺傳基因嗎？醫生們過去認為不會有什麼影響，現在他們對此不十分肯定了。
世界首例試管嬰兒路易士·布朗出生後２４年的時間�，成千上萬想做父母親的人們得到科學家們的保證說，試管內受精對基因不會有什麼額外的危險。無論精子如何與卵子結合--是否在女人體內還是在較硬的試管壁上，（即使精子需外力幫助才與卵子結合），大自然都同樣會阻止嚴重變形的基因分娩，有了這樣的允諾和保證，試管嬰兒的出生在20世紀80年代早期由每年的百餘例上升到現如今的數萬例。
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 straightforward 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 cognitive problems．
但上周的《新英格蘭醫學雜誌》有兩篇報告指出：這種傳統的說法也許是錯誤的。在第一篇研究報告中，英國和澳大利亞的醫生們發現，直接的試管受精和通過更具侵入性的技術--把精液通過注射直接與卵子相遇的方法而出生的嬰兒，有8.6％存在著主要由出生造成的缺陷的危險性--包括心臟、腎功能不正常、裂齶、男孩隱睾症等。而正常受孕出生的孩子這種現象的比率只為4.2％。第二個研究報告是由"美國疾病控制與預防中心"主持作出的。報告指出，通過醫生們所謂"協助生育技術"的方法而受孕出生的嬰兒出生時低體重或嚴重低體重的危險是正常情況的2.6倍。這是引起心臟病和認知能力問題的危險因素。
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．
我們有充足的理由對以上兩種研究嚴肅對待。例如：有關低體重出生研究方面，研究者們已然考慮到這樣的事實，即那些想通過醫學手段而受精生育的夫妻們年齡比一般生育年齡大些，而且一次多胎--雙胞胎、三胞胎等等。即使他們避免了這些因素，但是通過"協助生育技術"生育的嬰兒與正常生育的嬰兒之間仍然存在差異。
But there's no need to panic．Independent experts are quick to point out that the reports are hardly definitive．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 infertility，and you're comparing them with women who don't have the disease．"
Some of the same caveats 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．
但也沒有必要過分恐慌。其他專家們迅速指出這些報導絕不是確定性的。尋求生育幫助的夫婦並不僅僅是年齡偏大的，他們也是明顯的不育夫婦。"科羅拉多生育醫學研究中心"負責人威廉姆·斯庫克拉夫特博士說："你們是把兩類不同的病人進行對比。你們這兒有的是些患有不孕疾病的婦女，而你們卻把她們與那些根本沒有不孕症的婦女進行對比"。
專家們說，一些同樣的防止誤解的說明適用於出生缺陷研究。在這�，較早期的研究發現：試管嬰兒與正常嬰兒沒有重大的區別，而且新研究並沒有糾正這樣的事實，即尋求醫學手段而受孕的婦女首先她們本身的生育系統有問題。
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 reassuringly small．And even if the danger is twice what doctors previously believed，91% of ART babies would still be born perfectly 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．"
即使這些新研究被後期的研究所證實--在澳大利亞和美國有關不孕專案的研究已經在進行，通過醫學受精生育的孩子的出生會有缺陷危險仍然肯定是極小的。即使這種危險是醫生們先前相信的兩倍，但91％這類出生的嬰兒仍然完全健康。紐約基督教長老會醫院婦女不孕科主任--茲夫·羅森瓦克斯博士說："如果你問一對夫婦她們願意一生不要孩子，還是願意生育一個孩子，而且有多於90％的可能孩子是正常的，我想他們肯定會選擇要孩子。"
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