大麻，這種既可以用于娛樂，又可以用于醫療的物質，在過去幾年里行情一直見漲。美國各州都在（以某些形式）推行它的合法化。而合法大麻的銷售額預計將在2017年達到驚人的100億美元。不過，這種植物的繁榮對公眾健康的長期影響仍然不甚明朗——而最新的研究顯示，很大一部分年輕孕婦都在使用大麻，隨之引發的疑問是：它會對這些準媽媽的胎兒產生何種影響？

哥倫比亞大學（Columbia University）的研究人員發現，3.9%的孕婦（以及7.6%處在生育年齡的非孕婦）在2007年至2012年間使用過大麻。研究作者寫道：“從2002年到2014年，有過大麻使用經歷的孕婦人數增加了62%。大麻在18歲到25歲的女性中最為流行，這意味著年輕女性更有可能在懷孕期間使用大麻。”

數字本身并不至于引發恐慌。正如作者指出，有關大麻對健康影響的研究仍處于相對起步階段。不過已有一些研究推測，孕期使用大麻與新生兒體重較輕、大腦發育程度較低或有關聯。

孕婦大麻使用量增加的情況是否屬于藥物濫用，目前也難以界定。例如，醫用大麻最普遍的用法是緩解惡心和焦慮（這倆都是懷孕的常見反應），這或許可以部分解釋用量增加的原因。不過，正如哥倫比亞大學的研究人員指出的那樣，由于大麻在社會上的風靡，我們有必要密切關注使用者的身份，以及它可能給健康帶來的目前未知的潛在影響。（財富中文網）

譯者：嚴匡正

Marijuana—recreational and medicinal alike–has been on a tear over the past several years. States are legalizing it (in some form or another) left and right; legal cannabis sales are projected to reach an astounding $10 billion in 2017. But the weed boom’s long-term effect on public health is still murky—and a new study suggests that a larger share of younger, pregnant women are using marijuana, raising questions about how its use may affect the fetuses of expectant mothers.

Columbia University researchers found that 3.9% of pregnant women (and 7.6% of non-pregnant women of reproductive age) reported using marijuana in the previous month between 2007 and 2012. “Among pregnant women, the prevalence of past-month marijuana use increased 62% from 2002 through 2014. Prevalence was highest among women aged 18 to 25 years, indicating that young women are at greater risk for prenatal marijuana use,” wrote the study authors.

The numbers aren’t a cause for alarm in and of themselves. As the authors note, marijuana health effect research is relatively new. But there are some studies which suggest there may be a relationship between marijuana use during pregnancy and lower birth weight or brain development in offspring.

It’s also unclear that the increased marijuana use by pregnant women represents drug abuse; for instance, nausea and anxiety (both common among pregnancy) are among the most common symptoms of medical marijuana users, which may in part explain the increase in usage. But, as the Columbia researchers note, as cannabis use balloons across society, it’s important to keep tabs on who’s using it—and on potential health effects we don’t currently know about.