Want your baby's IQ to be a few points higher? Then keep it away from chemicals in household items like shower curtains, nail polish, and dryer sheets during pregnancy, a new study says. Researchers at Columbia University came to this conclusion after analyzing 328 women and their kids in New York City, CTV News reports. The research team measured how much the moms were exposed to chemicals called phthalates during the third trimester of pregnancy, and then, seven years later, gave their children IQ tests. Kids in the top 25% of chemical exposure scored 6.6 to 7.6 points lower. "The magnitude of these IQ differences is troubling," a senior study author tells Science Daily. "A six- or seven-point decline in IQ may have substantial consequences for academic achievement and occupational potential."
So what should pregnant women do? Avoid scented products; plastics labeled 3, 6, or 7; and "microwaving food in plastic," an epidemiologist involved in the study tells the Guardian. It's smart to store food in glass containers rather than plastic ones, she adds. Meanwhile, certain phthalates have been banned in American children's toys and other childcare products, and linked to diabetes, negative hormone effects, and a decline in child cognitive and motor development. Yet the chemicals aren't usually labeled on US products, and officials have never warned pregnant women about them. The new research may not tip the scales, either: "This study adds usefully to our knowledge," says a professor, but is "not entirely consistent" and "may in part reflect ... coincidental effects." (See why toys send kids to the ER every three minutes.)