There have been no studies of the effects of a low carbohydrate diet on pregnancy, so its effect on the fetus, if any, is unknown.

目前还没有关于怀孕时低碳水化合物饮食影响的研究，因此如果它对胎儿有什么影响也是不知道的。

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Within the medical profession, some have raised concerns about the unknown effects of the additives in the vaccines, in particular a substance called squalene.

在医学界，有些人已经对疫苗中的添加物，尤其是一种名为角鲨烯的物质的不明影响表示了担忧。

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But the study also found that these chemical reactions produce byproducts with unknown and possibly harmful effects on health.

但是这项研究同样发现了这些化学反应产生了未知且有可能对身体有危害影响的副产物。

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The anti-flush drug, they argued, is untested, and its potential cardiovascular effects are unknown.

FORBES: Magazine Article

Laboratory modification introduces alien and unnatural genes into crops, it is argued, where their eventual effects are unknown.

ECONOMIST: In defence of the demon seed

Other risks include the unknown effects that healthcare reform will have on drug companies.

FORBES: Pfizer Learns To Live With Leaner Lipitor Cash Cow