December 1, 2007
For Those Struggling to Get Pregnant, Chemicals Are Just One Potential Cause
At age 37, Tucsonan Erica Koerber knows she probably won't get pregnant. Blame the hormones in her body -- and maybe, just maybe, the chemicals in her environment.
Koerber, chief operating officer for a local defense contractor, has premature ovarian failure, a disease striking 1 in every 100 women ages 30 to 40.
The lists of possible causes of these ailments is long. Premature ovarian failure can be caused by autoimmune disorders, genetics, thyroid dysfunction, viral infections and eating disorders, to name a few, says the American Pregnancy Association.
But increasingly, researchers around the globe are also looking at toxic chemicals, many of them commonly used at home, as potential causes of these and other ailments that make it difficult or impossible for women to get pregnant.
Before Koerber read several reports on fertility, the thought that chemicals could be causing her problems hadn't entered her mind. She was more likely to suspect genetically engineered or chemically altered food, such as growth hormones added to chicken and cattle.
Now, she said, "My problem could be environmental. My problem could be generational. My mother and my grandmother had breast cancer, and breast cancer is endocrine-related. My problem is hormonal-based and endocrine-based."
Difficulty in getting pregnant
It's not clear from studies whether women's infertility has risen or fallen over the past few decades. But a noticeable increase has occurred since the 1980s in impaired fecundity, a related problem involving physical difficulty in getting pregnant, federal statistics show.
Decreased fertility and reproductive-tract abnormalities have been documented in wildlife species including birds, fish, shellfish and mammals that have been exposed to a wide array of chemicals, including many that are commonly known as endocrine disruptors. Those are chemicals that interfere with the body's natural hormones.
Human studies on such issues are much rarer.
Still, in 2005, a group of 40 U.S. scientists met in San Francisco and reported that some chemical exposures evidently cause problems to the human reproductive system, although toxins aren't likely to be the only factor.
Age, heredity, lifestyle, underlying disease, nutrition and reproductive tract infections are other likely contributors.
"What proportion of infertility today is environmentally induced is a question of profound human, scientific and public policy significance," said their report, adding that the link seems to be stronger than most people realize.
Hard to pinpoint 1 cause
Symptoms like Koerber's are consistent with those that could be caused by endocrine disruptors, said one of those scientists, Shanna Swan, who has conducted major studies on fertility issues and endocrine disruptors.
But it usually is not possible to pin a specific cause to problems in a single person because so many potential causes exist, said Swan, a professor of obstetrics and gynecology and environmental medicine at the University of Rochester in New York.
And an official with the Tucson clinic that has treated Koerber for her infertility problems said she believes that far more serious causes of infertility exist than chemicals. They include obesity, lack of exercise, stress, smoking and sexually transmitted diseases.
"Do I think that toxins can play a role in infertility? You betcha," said Holly Hutchison, managing partner and a geneticist for the Reproductive Health Center here.
But she said there are bigger factors: "If we had a society that could get rid of its foul habits and become healthier and less stressed overall, I think you would see a reduction."
Koerber said she was shocked to learn a year ago of her fertility problems. She does not smoke. She has exercised as much as three hours a day and feels healthy and youthful. She tries to eat healthfully, living as a near-vegetarian relying heavily on whole grains, fruits and vegetables, mostly organic.
For many years, she had gone to annual checkups in which doctors told her she was in excellent health and was a good bet to get pregnant.
Now, after years have passed with no pregnancy, Koerber and her partner, John Lombardi, might get eggs donated, and have screened potential donors. If that doesn't work, the couple will consider adoption.
Koerber took a 10-week mind-body fertility program with eight other infertile women this fall, in hopes of boosting her chances through stress management and relaxation techniques. She was shocked to learn that at age 37, she was the second-oldest person there and that many of the women were in their 20s.
Younger women affected
But if national statistics are any indication, the participants' ages were no surprise. Over the past two decades, impaired fecundity -- infertility's first cousin -- has risen most rapidly among women under 25, about 42 percent from 1982 to 1995, the federal Centers for Disease Control and Prevention says. That has triggered widespread concern that problems with human reproduction are growing.
But Hutchison, of Tucson's Reproductive Health Center, said that if a trend exists toward increased child-bearing problems for women, it is fueled primarily by women waiting until they are older to conceive.
Also, she said, "Now, there is more awareness. If people are not pregnant in six months, they go see more people, they report it," Hutchison said.
Array of studies raise questions
In the 1990s and this decade, a flood of studies raised questions about human fertility.
Early on came warnings of declining sperm counts, based on separate reviews of dozens of studies showing that sperm counts had dropped 50 percent throughout the Western world over five decades.
The studies were controversial, however, because not all the data were gathered in the same manner, leaving Stanford University to say that scientific uncertainty remains.
This year, researchers reported 1 percent annual declines in testosterone counts in men in Massachusetts, Denmark and Finland for up to 50 years.
Researchers in Denmark and Finland theorize that rising testicular-cancer rates in Western nations are also part of a broader pattern of apparently increasing male-reproductive problems.
Also this year, more than 400 scientists, health-care professionals, clinicians, community group representatives and others gathered in San Francisco for a summit on environmental challenges to fertility and reproductive health.
Organizers listed 20 compounds or classes of chemicals as having effects on animal or human reproductive problems. Effects include chromosome abnormalities, miscarriages, decreased sperm quality, fetal loss, menstrual irregularities, hormonal changes and altered sex ratios.
"The way we thought about it before is that one chemical causes one outcome," said Tracey Woodruff, an obstetrics and gynecology professor at the University of California-San Francisco. Now, they're reconsidering. "If you get exposed at a susceptible period, when the reproductive system is forming," there may be more risk that numerous, related problems will result, she said.
A federal health official is sympathetic to the theory that chemicals can lead to infertility, but said there hasn't been much money in recent years for the research needed to pin it down.
It is clear that environmental exposures can affect a child's development, as well as the reproductive years for males and females, said Jerrold Heindel of the National Institute of Environmental Health Sciences in North Carolina.
"The more data we get, the bigger the effect of environment seems to have on diseases in general," said Heindel, a scientific program administrator. "I believe the same will be true for infertility."
--Contact reporter Tony Davis at 806-7746 or [email protected]