A recent survey suggests that most doctors don’t discuss exposure to pollutants with their pregnant patients. (iStock)

Leading up to and during pregnancy, women are told to avoid alcohol and cigarettes, to make sure they get enough folate and omega-3 fatty acids, and to get adequate sleep and exercise. Most are told little or nothing about reducing their exposure to chemicals despite evidence suggesting that ingredients in plastics, vehicle exhaust and cosmetics additives can have profound impacts on babies’ health.

In recent years, the field of ­maternal-fetal medicine has started to respond. In 2013, the American College of Obstetricians and Gynecologists issued a committee opinion, reaffirmed this year, “calling for timely action to identify and reduce exposure to toxic environmental agents while addressing the consequences of such exposure.” The International Federation of Gynecology and Obstetrics voiced a similar opinion in 2015, and the following year nearly 50 prominent U.S. doctors and scientists created Project TENDR: Targeting Environmental Neuro-Developmental Risks to call for reducing chemical exposures that can interfere with fetal and children’s brain development.

Yet, a recent survey suggests that most doctors don’t discuss exposure to pollutants with their pregnant patients.

“Fetal development is a critical window of human development, and so any toxic exposure during that time, during pregnancy, doesn’t only have a short-term effect at that moment, but really an effect that lasts the entire lifetime,” said Nathaniel DeNicola, who was on the committee that reaffirmed the ACOG opinion.

In 2011, University of California at San Francisco (UCSF) researcher Tracey Woodruff and colleagues reported finding traces of dozens of harmful chemicals in 99 percent or more of the 268 pregnant women whose urine they analyzed; among them were organochlorine pesticides, perchlorate, phthalates and cancer-causing compounds found in vehicle exhaust and smoke.

With so many chemicals in the environment — more than 80,000 are registered for use in the United States — it’s impossible to determine the health impact, if any, of each. But researchers have found a variety of links, including between some pesticides and impaired fetal growth and neurodevelopment; between phthalates (used in many plastics) and increased risk of premature birth and impaired neurodevelopment; and between fine-particle air pollution and altered expression of genes that influence neurodevelopment.

More research has been done on animals than on humans: Epidemiologic studies are slow, costly and often difficult to conduct, and interventional studies are virtually impossible because of ethical concerns about intentionally exposing people to chemicals suspected to be harmful. But based on the research to date, experts such as Woodruff recommend that patients avoid many chemicals to the extent that they can because avoiding them can’t hurt and may benefit health.

“When I am faced with counseling somebody, I can’t say, ‘I know for sure that if you avoid these things, you are going to avoid your child having abnormal neurodevelopment,’ ” said Marya Zlatnik, an obstetrics professor and maternal-fetal medicine specialist at UCSF. “But based on the science that’s there, it’s clearly very concerning that these chemicals are causing a variety of health problems, and to the best of our knowledge, the way to avoid that is to avoid these chemicals.”

DeNicola, an assistant professor of obstetrics and gynecology at the George Washington University School of Medicine & Health Sciences, compares the issues of exposure levels to drinking alcohol during pregnancy. “We know there’s a certain dose of alcohol that is going to cause fetal alcohol syndrome and create problems. We don’t know what the safe dose would be, so the recommendation is just to avoid alcohol,” he said, though most doctors would not raise concerns over pregnant patients having an occasional glass of wine. Similarly, he said, “we know the heavy metals and phthalates are toxic at some level. Since we don’t know the safe amount, we try to just avoid it as much as possible.”

While scents in cosmetics are a source of phthalates, a woman who wears perfume on special occasions is not what DeNicola is worried about. “It’s more a guidance to avoid the routine daily exposures that over the long term add up to something that’s clinically relevant.”

Philip Landrigan, dean for global health at the Icahn School of Medicine at Mount Sinai in New York, said, “For years and years, we’ve talked about alcohol, tobacco and recreational drug use — limiting all those during pregnancy,” he said. “But in the last decade, ACOG has come to realize that lead and pesticides and PCBs and mercury that are found in certain fish — that all of those pose a harm to the fetus in the womb and that it makes an awful lot of sense for women to minimize their exposure to those chemicals.”

Zlatnik now includes a brochure about chemical exposures in the packet that she gives out at initial prenatal appointments. It won’t make a difference for every woman, she says, pointing out that patients who aren’t literate or who are struggling to make ends meet may have a harder time than others prioritizing chemicals as something to worry about. “Not that you can really buy your way out of the problem, but at least having financial resources does make it easier to avoid some of the toxins,” she says.

While chemicals are virtually impossible to avoid completely, people can reduce contact with some of the most harmful and common toxins. Project TENDR, for instance, suggests ways for preventing exposure to pesticides and chemicals in food, furniture and personal care and cleaning products.

UCSF’s “Toxic Matters” website also offers practical recommendations. And SafetyNest, a website that Woodruff is advising, will aim to provide doctors and pregnant women easy access to research on prenatal environmental health. Its founder, Alexandra Destler, expects the full site to launch in the fall.

DeNicola says efforts to get information on chemicals to pregnant women can’t happen soon enough. “The toxic burden on pregnant women is a clear and really immediate health-care concern,” he says. “It’s critically important that the doctors who take care of pregnant women and young children know about the health effects and can counsel patients about it.”

Some tips

To lessen exposure to chemicals during pregnancy, consider this advice from Project TENDR, UCSF’S Toxic Matters series and individual experts:

●Remove shoes before going into the house to avoid tracking in dust and dirt that can contain contaminants.

●Wash hands frequently, especially before eating. “We are touching things all the time that likely have some [chemical] residue on them,” said George Washington University’s DeNicola.

●Dust and wet-mop regularly. “Chemicals love to hang out in dust,” said UCSF’s Woodruff.

●Don’t heat food in plastic, and reduce the amount of plastic that come into contact with food generally. “Don’t ever cook or reheat things in plastic, because the components of the plastic will come into the food or beverage. They will, guaranteed. Some more, some less — but you don’t need any of it,” said Bruce Blumberg, a professor of developmental and cell biology at the University of California at Irvine.

●Eat low on the food chain — i.e., emphasize plant-based foods, and choose smaller fish such as sardines because of the risk for mercury that can accumulate in larger fish, advises Woodruff.

●Look for organically grown food, which can reduce your exposure to pesticide residues.

●Be cautious about using nonstick cookware. This is more a recommendation about avoiding the unknown, Woodruff says. “Companies have stopped using Teflon and some of the similar [nonstick] chemicals in new cookware. But there is not very much science about the newer chemicals used in nonstick cookware. Avoiding their use will get you out of the guessing game of whether they will be identified as harmful or not.”

●For everyday use, choose cosmetics and cleaning products that are fragrance-free. That means avoiding perfumed products but also unscented ones, which DeNicola said often have scented phthalates to mask the scent of other ingredients. He advises patients to check for diethyl phthalate, or DEP, “since this is the most common phthalate in fragrances and might be included in something still labeled ‘unscented.’ ”

“The only thing that really counts as safe is fragrance-free, in terms of phthalates,” he said. He emphasizes that routine exposure is the concern, so an occasional scented lotion or monthly cleaning are not likely to present much risk.

●If you live in urban or densely populated suburban areas, avoid exercising outside when vehicle pollution levels are higher — i.e., during rush hour.