原文: Can Caffeine Cause Miscarriages?

What’s this about caffeine causing miscarriages? How much caffeine puts a woman at risk? Or shouldn’t you consume any at all?

You may have heard about a California study showing that drinking more than two cups of coffee a day can nearly double the risk of miscarriage. Investigators from Kaiser Permanente Research Division in Oakland, Calif. compared the miscarriage rates among more than 1,000 women, including those who consumed caffeine in all forms while pregnant and those who eliminated it from their diets. They found that women whose daily caffeine consumption was 200 mg or more (the amount in two cups of coffee or five cans of cola) had twice the risk of miscarriage as women who consumed no caffeine. They also found a 40 percent increased risk among women who consumed caffeine at a daily dose less than 200 mg, compared to those that consumed none. The study was published in January 21, 2008 in the American Journal of Obstetrics and Gynecology.

This isn't the first study to connect caffeine with miscarriages, but it is unlikely to be the last word on the subject: other studies have found no association at all, while still others have linked miscarriages only with higher doses of caffeine, 300 mg or more.

Some specialists who commented on the study noted that women who consume caffeine during pregnancy are also more likely to smoke and drink alcohol, both known risk factors to the baby. Exactly how caffeine could lead to miscarriage isn't known, but it is a stimulant that often causes anxiety, insomnia, increased blood pressure, heart rate and urine production. Some of these changes may affect the baby as well as the mother.

I would advise keeping caffeine intake low during pregnancy. (Remember that tea, chocolate, and some non-prescription drugs also contain it.) Some doctors think it's time to advise pregnant women to eliminate caffeine entirely for the duration. That may be prudent since no study has yet established a safe level of caffeine consumption during pregnancy. But worried women who have been consuming caffeine should understand that most miscarriages are caused by chromosomal abnormalities; of the 172 miscarriages that occurred during this study, 130 occurred among women who consumed no caffeine at all or less than 200 mg per day.

Andrew Weil, M.D.

译文: 咖啡因会导致流产吗？

     问：咖啡因会导致流产这一说法是怎么一回事？妇女摄入多少咖啡因才是有危险的？是不是一点都不能碰呢？

     答：你可能阅读过一则有关咖啡因的研究报告，报告显示，每天喝两杯以上的咖啡差不多可以使流产的几率加倍。来自哈里发奥克兰市凯萨医疗机构分部的研究人员曾对比了1000名妇女的流产率数据，其中包括那些在怀孕期间以各种形式摄入咖啡因的妇女和那些将咖啡因排除在菜单外的妇女，他们发现，那些每天咖啡因摄入量达到200毫克或以上（相当于2杯咖啡或5罐可乐的咖啡因含量）的妇女，其流产的危险是那些不摄入咖啡因的妇女的两倍。他们还发现，即使每天摄入咖啡因的含量少于200毫克的妇女，也比那些从不摄入的妇女多40%的危险。这一研究于2008年1月21日首次发表于《美国产科与妇科学杂志》。

     这不是第一项将咖啡因与流产联系起来的研究，但也不可能是对这项研究的最终定论。还有其它研究证明两者之间毫无关联，另有一些认为流产只是与高剂量的咖啡因有因果关系，比如摄入量达到300毫克或更多。

     一些专家对此研究颇有批判，指出在怀孕期间摄入咖啡因的妇女很有可能也会吸烟和酗酒，众所周知，它们对宝宝也是有害的。况且，究竟咖啡因如何导致孕妇流产的原因和过程我们尚不可知，我们只知道，它可以被视为一种兴奋剂，从而引起焦虑，失眠，血压升高，心跳加速，尿量增多，其中一些变化可能会影响婴儿和母亲的身体状况。

     我建议，怀孕期间尽量少摄入咖啡因（记住，茶，巧克力和一些非处方药同样含有咖啡因）。一些医生认为，孕妇最好在这段时间内完全放弃咖啡因。这是谨慎之举，因为还没有一项研究给出过一个怀孕期间咖啡因摄入量的安全标准。有些妇女担心自己已经摄入过咖啡因，会导致流产，但是，她们也要明白，大多数流产都是由于染色体突变而引起的。研究表明，172起流产案件中，有130起发生在那些没有摄入过咖啡因或每天咖啡因的摄入量低于200毫克的妇女身上。

     安德鲁·威尔医学博士