New Study Finds Miscarriage Risk Increases With BPA Exposure
Women exposed to high levels of bisphenol A (BPA) early in their pregnancy had an 83 percent greater risk of miscarriage than women with the lowest levels, according to new research.
The scientists said their new study adds to evidence that low levels of the ubiquitous chemical, used to make polycarbonate plastic and found in some food cans and paper receipts, may affect human reproduction.
The study involved 115 pregnant women who had visited a Stanford University fertility clinic within about four weeks of fertilization. The more BPA detected in the women’s blood, the higher their risk of miscarriage, according to the researchers.
“Couples suffering from infertility or recurrent miscarriages would be best advised to reduce BPA exposure because it has the potential to adversely affect fetal development,” wrote the scientists, led by Dr. Ruth Lathi, a Stanford University associate professor of obstetrics and gynecology. The study was published in the journal Fertility and Sterility.
However, the new study doesn’t mean BPA causes miscarriages. The findings were based on one or two blood tests early during the pregnancies, and more women would need to be tested to see if the results are replicated.
In addition, the women who participated were likely at high reproductive risk because they had been treated at a fertility center. That means the findings may not be relevant for the general population, said Emily Barrett, an assistant professor of obstetrics and gynecology at the University of Rochester’s Medical Center. She was not involved in the study.
Sixty-eight of the 115 women had miscarriages, which is roughly three times the rate of the U.S. population.
“This is not a typical population since these are women seeking fertility care,” Barrett said.
Despite the limitations, this is “another piece of evidence” linking the chemical to pregnancy problems, Barrett said.
In 2005, a smaller study in Japan found that 45 women who had three or more first-trimester miscarriages had three times more BPA in their blood than 32 women with no history of pregnancy problems.
For the new study, the scientists divided the women into four groups based on their BPA measurement, then compared their miscarriage rates. The women with the highest exposures had an 83 percent higher risk of miscarriage, while those in the second and third groups had increased risks of 58 percent and 30 percent.
“This study has the same flaw as other studies that attempt to measure BPA in blood at a single point in time and statistically associate that limited data with a health effect—in this case, miscarriage,” said Kathryn St. John, a spokesperson for the American Chemistry Council, which represents chemicals manufacturers, in a prepared statement.
Most miscarriages occur within the first seven weeks of pregnancy. The early stage tested in the new study is “certainly one period that’s very important” for measuring exposures, Barrett said.
About 90 percent of people tested in the U.S. have BPA in their bodies.
Barrett said that most researchers agree the current standard for measuring BPA in people is testing urine for total BPA, which includes both free form and conjugated. Free BPA is the form that is estrogenic and acts on the body. Lathi and colleagues measured only the conjugated form in blood.
University of Missouri professor Frederick vom Saal, a co-author of the study, said there are pros and cons to any measurement of BPA in people. Blood samples are more likely to be contaminated with free BPA from the environment but the study avoided that problem by looking only at conjugated, he said.
There is an ongoing scientific dispute over whether traces of BPA can harm people. The U.S. Food and Drug Administration (FDA) said BPA is safe at the low amounts that people are exposed to through foods. The agency released a study earlier this year that found BPA doesn’t affect the health of rats fed low doses. However, some academic researchers have called the FDA study flawed.
In 2008, a federal agency, the National Toxicology Program, determined that there was “negligible concern” that exposure of pregnant woman to BPA will harm fetuses or infants. Two years later, the Environmental Protection Agency announced an action plan to further investigate BPA, declaring it a chemical of concern.
Known risk factors for miscarriage include obesity, problems with the mother’s hormones, reproductive organs and immune system, smoking and drug and alcohol abuse.
Lathi and colleagues did not investigate how the women may have been exposed to BPA. She said that in the future the researchers would like to examine whether avoiding BPA during pregnancy lowers miscarriage risk.
“These are just regular pregnant women with what we think is regular exposure,” Lathi said. “There is nothing to make us think that our patients are more highly exposed than anyone else in the U.S.”
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Since even moderate-intensity workouts offer a slew of benefits, walking is a good choice for people looking to stay healthy.
How to Rock Your Walk<p>Walking isn't just fun and healthy. It's accessible.</p><p>"Walking is cheap," says Dr. John Paul H. Rue, a sports medicine doctor at <a href="https://mdmercy.com/" target="_blank">Mercy Medical Center in Baltimore</a>. "You can do it anywhere at any time; [it] requires little to no special equipment and has many of the same cardio benefits as running or other more intense workouts."</p><p>Want to up your walking game? Try the tips below.</p>
Use Hand Weights<p>Cardio and strength training can go hand-in-hand when you add weights to your walk.</p><p>A <a href="https://journals.lww.com/acsm-msse/Fulltext/2019/03000/Associations_of_Resistance_Exercise_with.14.aspx" target="_blank">2019 study</a> found that weight training is good for your heart, and <a href="https://www.mayoclinicproceedings.org/article/S0025-6196(17)30167-2/abstract" target="_blank">research</a> shows it reduces the risk of developing a <a href="https://www.healthline.com/health/nutrition-metabolism-disorders" target="_blank">metabolic disorder</a> by 17 percent. People with metabolic disorders have a higher chance of being diagnosed with high cholesterol, high blood pressure, and diabetes.</p><p>Rue suggests not carrying weights for your entire walk.</p><p>"Hand weights can give you an added level of energy burning, but you have to be careful with these because carrying [them] over a long period of time or while walking could actually lead to some overuse injuries," he says.</p>
Make It a Circuit<p>As another option, consider doing a circuit. First, put a pair of dumbbells on your lawn or somewhere in your home. Walk around the block once, then stop and do some bicep curls and tricep lifts before walking around the block again.</p><p>Rue recommends <a href="https://www.healthline.com/health/exercise-fitness/running-with-weights" target="_blank">avoiding ankle weights</a> during cardio workouts, as they force you to use your quadriceps rather than hamstrings. They can also cause muscle imbalance, according to the <a href="https://www.health.harvard.edu/staying-healthy/wearable-weights-how-they-can-help-or-hurt" target="_blank">Harvard Health Letter</a>.</p>
Find a Fitness Trail<p>Strength training isn't limited to weights. You can get stronger by <a href="https://www.healthline.com/health/bodyweight-workout" target="_blank">simply using your body</a>.</p><p>Often found at parks, fitness trails are obstacle courses with equipment for pullups, pushups, rowing, and stretches to build upper and lower body strength.</p><p>Try searching "fitness trails near me" online, checking out your local parks and recreation website, or calling the municipal office to <a href="https://calisthenics-parks.com/" target="_blank">find one</a>.</p>
Recruit a Friend<p>People who workout together stay healthy together.</p><p><a href="https://bmcgeriatr.biomedcentral.com/articles/10.1186/s12877-017-0584-3" target="_blank">One study</a> showed that older adults who exercised with a group improved or maintained their functional health and enjoyed their lives more.</p><p>Enlist the help of a walking buddy with a regimen you aspire to have. If you don't know anyone in your area, apps like <a href="https://www.strava.com/" target="_blank">Strava</a> have social networking features so you can get support from fellow exercisers.</p>
Try Meditation<p>According to the <a href="https://www.nccih.nih.gov/research/statistics/nhis/2017" target="_blank">2017 National Health Interview Survey</a>, published by the National Institutes of Health, meditation is on the rise, and for good reason.</p><p>Researchers <a href="https://pubmed.ncbi.nlm.nih.gov/29616846/" target="_blank">found</a> that mind-body relaxation practices can regulate inflammation, <a href="https://www.healthline.com/health/biological-rhythms" target="_blank">circadian rhythms</a>, and <a href="https://www.healthline.com/health/glucose" target="_blank">glucose</a> metabolism, as well as lower <a href="https://www.healthline.com/health/high-blood-pressure-hypertension" target="_blank">blood pressure</a>.</p><p>"Any form of exercise can be turned into a meditation of some type, either by the surroundings you are walking in, like a park or trail, or by blocking out the outside world with music on your headphones," Rue says.</p><p>You can also play a podcast or download an app like <a href="https://www.headspace.com/headspace-meditation-app" target="_blank">Headspace</a> that has a library of guided meditations to practice while you walk.</p>
Do Fartlek Walks<p>Typically used in running, fartlek intervals alternate periods of increased and decreased speed. These are <a href="https://www.healthline.com/nutrition/benefits-of-hiit" target="_blank">high-intensity interval training (HIIT)</a> workouts, which allow exercisers to accomplish more in less time.</p><p><a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154075" target="_blank">One study</a> showed that 10-minute interval training improved <a href="https://www.healthline.com/health/metabolic-syndrome" target="_blank">cardiometabolic</a> health, or lowered the risk of heart disease, stroke, and diabetes, just as well as working out at a continuous pace for 50 minutes.</p><p><a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0111489" target="_blank">Research</a> also shows that HIIT workouts increase muscle <a href="https://www.healthline.com/health/fast-twitch-muscles" target="_blank">oxidative</a> capacity, or the ability to use oxygen. To do a fartlek walk, try walking at an increased pace for 3 minutes, slow down for 2 minutes, and repeat.</p>
Gradually Increase Pace<p>A faster walking pace is associated with a lower risk of <a href="https://www.healthline.com/health/copd" target="_blank">chronic obstructive pulmonary disease (COPD)</a> and respiratory diseases, according to a <a href="https://pubmed.ncbi.nlm.nih.gov/30303933/" target="_blank">2019 study</a>.</p><p>Still, it's best not to go from a stroll to an Olympic-worthy power walk in a day. Instead, increase your pace gradually to prevent injury.</p><p>"Start by walking at a brisk pace for about 10 minutes per day, 3 to 5 days per week," Rue says. "Once you've done this for a few weeks, increase your time by 5 to 10 minutes per day until you get to 30 minutes."</p>
Add Stairs<p>You've likely heard that taking the stairs instead of an elevator is a way to add more movement into your daily routine. It's also a way to step up your walking. Stair climbing has been shown to <a href="https://www.sciencedirect.com/science/article/pii/S2211335519301123?via%3Dihub" target="_blank">decrease the risk of mortality</a> and can easily add a bit more challenge to your walk.</p><p>If you don't have stairs in your home, you can often find them outside a local municipal building, train station, or at a high school stadium.</p>
Is Your Walk a True Cardio Workout?<p>Not all walks are equal. A walk that's too leisurely may not provide enough burn to qualify as cardio. To see if you're getting a good workout, try to <a href="https://www.healthline.com/health/how-to-check-heart-rate" target="_blank">measure your heart rate</a> using a monitor.</p><p>"A target goal for a good walking workout heart rate is about 50 to 70 percent of your maximum heart rate," Rue says, adding that maximum heart rate is <a href="https://www.healthline.com/health/fitness-exercise/fat-burning-heart-rate" target="_blank">typically calculated</a> by 220 beats per minute minus your age.</p><p>You can also monitor how easily you can carry on a conversation while you walk to gauge your heart rate.</p><p>"If you can walk and carry on a normal conversation, that's probably a lower intensity walk," says Rue. "If you are slightly breathless but can still have a conversation, that's probably a moderate workout. If you are out of breath and can't talk normally, that's a vigorous workout."</p>
Takeaway<p>By shaking up your routine, you can add excitement to your workout and reap even more rewards than a basic walk provides. Increasing the pace and intensity of a workout will make it more effective.</p><p>Simply pick your favorite variation to add some spice to your next walk.</p>
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