For a healthier pregnancy, get thee to a nature preserve.
Quick, picture a place where you feel calm and happy. A beach? The mountains?
Most people pick someplace outdoors, even though they spend the great majority of their days inside buildings. Many of them even exercise indoors!
But evidence is mounting that being outside, and especially exercising in a natural environment, improves mental and physical health, says Daphne Miller, M.D., a clinical assistant professor of family and community medicine at the University of California, San Francisco.
The outdoors has special benefits for moms-to-be.
"Many women get deconditioned during pregnancy," explains Miller. "They need incentives to get off the couch—and people who exercise outdoors are more inclined to repeat the experience." Open-air exercise may also help women who are struggling with prenatal depression or anxiety.
A review of 11 studies found that people who did their workouts in a natural setting felt happier and more energized than those who exercised indoors. Even brief sessions of "green" exercise are beneficial, especially when the natural area includes water, such as creeks or ponds.
Fresh air fundamentals
But why is a walk in the park such good medicine? One contributor is a healthier atmosphere: Outdoor air usually contains about half the pollutants of indoor air. Another is the vitamin boost from sun exposure. Research indicates that the vitamin D our bodies make when skin is exposed to sun has a more lasting effect than what we get from food and supplements.
Many moms-to-be—especially those with darker skin or who live in northern latitudes—don't get enough vitamin D, and deficiency is associated with higher rates of prenatal infections, preeclampsia, preterm birth and Cesarean section. Newborns whose moms were deficient are at risk for low calcium levels and skeletal abnormalities, such as rickets.
"While you should always avoid too much exposure, my advice to pregnant women is to get 10 minutes of sun on their arms and legs daily," Miller says.
Perhaps surprisingly, the benefits of being in nature include exposure to microbes like Mycobacterium vaccae, a soil bacterium that people may ingest or inhale when in natural environments. These bacteria seem to have antidepressant properties. In one study, researchers injected them into lab animals, which responded by becoming calmer and learning faster.
There's more: Volatile compounds called phytoncides, which are released into the air by trees such as cedar and pine, seem to enhance human immune function. Researchers in Japan, where nature walks are called shinrin-yoku, or "forest bathing," found that people who walked in the woods had healthier immune systems, lower blood pressure and lower levels of the stress hormone cortisol compared with people who walked in urban settings.
Lowering stress can be particularly important during pregnancy; one study found that children born to women with high cortisol levels tended to be more anxious. These findings, Miller says, shouldn't be surprising. We humans, after all, are "part of nature, we're from nature. When we get out there among the trees and have the wind in our hair and are breathing clean air, we're much more in balance and at peace."