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This is Scientific American's 60-Second Science. I'm Cynthia Graber. This will just take a minute.

Can we be too clean? According to what's called the hygiene¹ hypothesis, yes. Without being challenged as kids, our immune systems don't flourish. Scientists think it could be part of the rise of allergies² and asthma³.

Now a new study supports the hygiene hypothesis: infants in Uganda had a lower chance of developing the skin allergy⁴ condition eczema if their moms had helminth worm infections while pregnant. The research is in the journal Pediatric Allergy and Immunology.

A 2005 study showed that kids of women treated for worm infections had more eczema. Twenty-five hundred pregnant women took part in this follow-up research. Some got one worm-killing drug. Others took a different drug. And a third group received a placebo⁵. One drug nearly doubled the kids' risk of eczema. The other more than doubled the odds⁶.

Helminth worm infections can give the mothers symptoms such as mild anemia⁷ or stomach pain and vomiting⁸. Although many people have no symptoms at all. The scientists say more research is needed before they would recommend not treating worm infections. But the work lends additional support to the idea that hygiene may be a balancing act rather than a goal.

Thanks for the minute. For Scientific American's 60-Second Science, I'm Cynthia Graber.