Babies may breathe easier if mom avoids BPA, a chemical found in many kinds of plastic.

If a most-wanted list existed to target chemicals believed to damage children's health, bisphenol A, or BPA would be among the top entries on the list. A growing body of research is linking BPA exposure not just to diabetes, heart disease, and other adult ailments, but also to neurological impairment and developmental problems in children.

But BPA-laden baby bottles and food packaging aren't the first exposure route for babies. In fact, exposure starts much earlier, during a mother's pregnancy. Depending on the exposure and timing of exposure, whatever BPA a mother is ingesting could be setting her baby up for breathing problems. Research presented at the Pediatric Academic Societies' 2011 annual meeting in Denver speaks to that: Babies born to moms with higher BPA levels during pregnancy are more likely to experience wheezing early in life. "Rates of asthma in kids have more than doubled in the last few decades. It is not likely that our genes have changed that quickly, so many suspect that there are some environmental exposures that may be responsible for this increase," explains lead study author Adam Spanier, MD, PhD, assistant professor of pediatrics and public health sciences at Penn State College of Medicine.

Spanier and colleagues studied 367 children, 99 percent of whom were born to moms with detectable BPA levels in their urine during pregnancy. Twice a year for the next three years after giving birth, mothers kept track of and reported on any wheezing incidents in their children. "I decided to focus on BPA first because of a recent animal study that suggested that perinatal BPA exposure was associated with an experimental model of asthma in mice," Dr. Spanier says.

At 6 months of age, children born to mothers with higher BPA levels were twice as likely to suffer wheezing problems. (Wheezing babies can grow up to develop full-blown asthma.) Because researchers tested pregnant mothers at various points during their pregnancies, they were able to show that higher BPA levels 16 weeks into the pregnancy were more likely to lead to wheezing babies. High levels 26 weeks and beyond did not seem to have the same effect, meaning the timing of the prenatal chemical exposure matters. "This suggests that there are periods of time during pregnancy when the fetus is more vulnerable," Dr. Spanier says. "Exposure during early pregnancy may be worse than exposure in later pregnancy."

The bottom line?

"Consumers need more information about the chemicals in the products they purchase so they can make informed decisions," Dr. Spanier explains, noting that 90 percent of the U.S. population harbors BPA in the body.

Because BPA is a high-production volume chemical, it's turning up everywhere, including beach sand, drinking water, and the air. Discouraging, yes. But a study out of the Silent Spring Institute earlier this year provided solid evidence that avoiding plastic and packaged foods drastically lowers BPA levels in the body. This, in turn, will also help protect babies as they develop in a womb that's as BPA free as possible. It is tough to completely avoid BPA, since it is present in many consumer products, but Dr. Spanier recommends avoiding canned foods, trying to cut back on plastic products, and definitely avoiding microwaving in plastics or putting hot liquids in plastic.

Here's how you can reduce your exposure to BPA:

• Say "See ya!" to as much canned food as possible. The epoxy lining of most commercial canned food cans used for contains varying levels of BPA. Plus, a lot of canned food is also loaded with salt, so you win in more than one way by opting instead for fresh, unprocessed foods.

• Say no to unnecessary receipts. Thermal cash-register receipt paper is often coated with BPA, too. An Environmental Working Group analysis discovered that the BPA in cash-register receipts is sometimes up to 1,000 times higher than the amount found in the lining of canned food. BPA-free receipts are popping up (the paper boasts little red flecks in the paper to show it's BPA free), although some scientists are also concerned about chemicals replacing BPA in BPA-free products, saying there's not enough research to prove the replacements are safe. When in doubt, just say you don't need a receipt for nominal purchases.

• Be a skeptical server. As we head into picnic season, it's especially important to check plastic serving ware for potential BPA contamination. Avoid No. 7 plastics, and remember that this could mean not using plastic picnic wine glasses, pitchers, plates, and cutlery.