Posted: Nov 14, 2012 3:33 PM
Nov. 14, 2012 -- Many couples try month after month to become pregnant, and new research suggests that for some, the delay may be related to their exposure to chemicals found in the soil, water, and food supply.
These chemicals, called persistent organochlorine pollutants, may persist in the environment for decades. Some, such as persistent lipophilic organochlorine pollutants, accumulate in fatty tissues in animals, while perfluorochemicals or PFCs are used in clothing, furniture, adhesives, food packaging, nonstick cooking surfaces, and electrical wire insulation.
The new study shows that men and women with high levels of these chemicals in their blood took longer to conceive than couples with lower levels. The effects seem to be more pronounced in men.
It is too early to say how or even if exposure to these ubiquitous chemicals affects a couple's ability to conceive. There is little we can do to reduce the levels already in our bloodstream. There are, however, many things we can change or do to increase the odds of becoming pregnant, including not smoking and maintaining a healthy body weight.
The findings are published online in Environmental Health Perspectives.
About 500 couples were followed for up to a year while trying to become pregnant.
Researchers analyzed their blood for a laundry list of chemicals, including organochlorines and PFCs. Women kept journals to record their monthly menstrual cycles and the results of their home pregnancy tests. The researchers estimated the couples' probability of pregnancy each cycle, based on their blood concentration of the compounds.
"Many of these chemicals are persistent in the environment, and we get them through dairy products and animal fat," says researcher Germaine Buck Louis, PhD. She is the director of the Division of Epidemiology, Statistics, and Prevention Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) at National Institutes of Health in Rockville, Md.
For starters, trim all excess fat from fish and meat. "If you eat that piece of meat with fat, you get an extra bump," Louis says. Other than that there is not all that much men or women can do today to lower levels of these chemicals in their systems.
So how do levels of these chemicals compare with other factors known to affect couples' ability to conceive? "They make it about 20% harder for these couples each cycle," she says. "The magnitude is comparable to cigarette smoking."
Many couples who have trouble conceiving will pursue fertility treatments. "Some studies have shown that couples with higher concentrations of some of these chemicals have decreased success with assisted reproductive technologies, too."
Now the team will be digging deeper into the same data set and looking at other lifestyle factors, such as alcohol, caffeine, and vitamins. "There may be something in your lifestyle that could mediate the effects of chemicals on conception," Louis says.
This study is a big deal, says Shanna Swan, PhD. She is a professor in the department of preventive medicine at Mount Sinai School of Medicine in New York City.
"Environmental chemicals can and do affect your fertility. That is the bottom line," she says. "This landmark study looks at the critical window when couples are trying to get pregnant." Other studies have looked at women who were already pregnant.
Many of these chemicals are hard (if not impossible) to avoid. "Try to avoid fatty meats, but there is nothing we can do about the ones [already] in our body," Swan says.
Sami David, MD, is a reproductive endocrinologist and pregnancy loss specialist in New York City. He routinely asks couples about their exposures to pesticides, solvents, and other chemicals at work or elsewhere.
The link is far from proven, and more studies are needed. His advice is to avoid chemicals where you can. This includes steering clear of secondary smoke, which contains toxic chemicals that can affect health and possibly chances of getting pregnant.
The findings are no reason to panic, says Gilbert Ross, MD. He is the medical director of the American Council on Science and Health, a nonprofit group in New York City.
"PFCs are used in the manufacture of nonstick surfaces, and the amount that shows up in the final product is barely detectable, even using modern analytical methods," he says. PCBs have been banned in the USA since 1978. "There is no evidence that the tiny amounts of PCBs still in our environment contribute to any adverse health effect."
"These traces of chemicals play no role in reproductive issues, including fertility," he says. But, "these chemicals are called 'persistent pollutants' because they do persist in the environment, [so] changing your diet, cutting out fat or avoiding healthy fish, will not have any near-term impact on the already-minuscule levels in our bodies."