Strong. When you hear that word, you probably think of an Olympic weightlifter, not a woman balancing a baby on her hip. It turns out you should revise that mental image — think of a mother grizzly when someone’s threatening her cubs, or British runner Paula Radcliffe winning the 2007 New York City Marathon 291 days after giving birth.
A growing body of research suggests motherhood shores up a woman’s strength in several ways (and no, not just in the whatever-doesn’t-kill-you-makes-you-stronger sense!). In fact, moms have such amazing abilities that scientists are now studying the ways that pregnancy, breastfeeding and mothering change our brains and bodies, for clues to new ways of treating diseases from Alzheimer’s to osteoporosis. Here’s a sampling of the surprising perks we enjoy in exchange for nurturing the next generation.
Giving birth and breastfeeding both seem to help reduce the likelihood of developing female cancers, according to Don Davis, past president of the Society of Obstetricians and Gynaecologists of Canada. “If you have a child before the age of 20, it reduces the odds of breast cancer by about one half,” he notes, adding that moms who give birth between 20 and 30 reap a smaller but still measurable benefit. A review of 47 different studies suggests breast cancer risk also drops about 4.3 percent for each year a woman spends breastfeeding.
Even if you waited until your mid-30s or later to become a mom, you’ll still reap other rewards — the more kids you have, the lower your risk of cancer of the uterine lining. “Pregnancy can reduce the incidence of endometrial cancer by 30 percent for a woman’s first birth, and by 25 percent for each successive birth,” Davis explains. And that’s not all. Giving birth seems to substantially decrease a woman’s chances of getting ovarian cancer: In one study reported in 1995, the risk dropped about 20 percent per full-term pregnancy, and breastfeeding offered a small added dose of protection.
Pregnancy and birth have a near-miraculous effect on the skeleton’s ability to build up bone — something it can’t do otherwise after reaching peak mass around our mid-20s. While a woman loses five to 10 percent of her bone within three to six months during breastfeeding (mom’s body borrows calcium from her skeleton and puts it in breastmilk), her bone mass bounces back almost as quickly, says Christopher Kovacs, a professor of medicine and endocrinology at Memorial University of Newfoundland in St. John’s. And pregnancy may bulk up bones even when mom’s not getting bone-building nutrients. Ordinarily, mice that lack vitamin D receptors have thin bones, but experiments show pregnancy bolsters their bone strength to normal levels, and the benefits linger after weaning.
While the drugs we have to treat osteoporosis can modestly build bone, they can’t perform such feats — which may explain why studies that have looked for links between risk factors and osteoporosis suggest that breastfeeding is either neutral or protective. In fact, in one trial, teen moms who breastfed had stronger bones three years after giving birth than those who bottle-fed. “There’s something about this loss and recovery that probably helps to strengthen the skeleton in the long run,” says Kovacs.
There may be a grain of truth in the myth that moms sprout an extra set of eyes! While trying to figure out why nursing rats are far more efficient hunters than virgin females, researcher Craig Kinsley and his colleagues narrowed the explanation to an improvement in vision. On average, mama rats catch crickets within 65 seconds, versus 270 for non-mothers, and only fail to find their prey when it’s so dark you can’t see your hand in front of your face. “We think what’s happening is the females are being able to detect the cricket better, through enhanced ability to see contrast or depth perception, or something like that,” explains Kinsley, a professor of neuroscience at the University of Richmond in Virginia.
Not a rat, you say? Well, cast your eye on this. After an article on Kinsley’s work appeared in Scientific American, the editors got a letter noting that one company routinely hired pregnant women to help perfect their high-definition TV technology — they were better at detecting distortions in the picture than other workers.
Vision isn’t the only sense honed by motherhood. University of Toronto researcher Alison Fleming discovered that new moms quickly learn to identify their own baby’s smell. Animal studies have also shown that after birth, new nerve cells take hold in an area of the brain that’s involved in detecting odours.
Feel like your brain moved out when you gave birth? In fact, pregnancy does temporarily sabotage certain kinds of memory and even shrinks your brain volume by about four percent. (No worries — it quickly returns to normal.) But in the long run, motherhood actually seems to change the brain in beneficial ways, says Liisa Galea, an associate professor of psychology at the University of British Columbia in Vancouver. For rats, at least, having babies improves both reference and working memory. (You use the former to remember where the parking lot is, and the latter to locate your car on a given day.) When rats learn where they can expect to find food in a maze, mothers are far better at remembering the route on subsequent trips than their childless sisters. “They’re more efficient,” Galea says. Moreover, moms retain that know-how well into old age. Recent research suggests being a mom may also add traffic lanes on the mental information highway — electrical messages seem to move along moms’ nerve cells in tandem more than they do in non-mothers.
Furthermore, motherhood could make the brain more resistant to a type of dementia. When Kinsley and his colleagues tested very old rats, they found two-time mothers not only outperformed non-mothers and one-time mothers on mental tests, but their brains also had lower levels of a protein that’s linked to Alzheimer’s disease.
While more research is needed to confirm the connection, some evidence hints that breastfeeding may reduce the risk of type 2 diabetes. (That’s important because dia-betes substantially increases the likelihood of many health problems, including heart disease.) A study of more than 150,000 women showed that the longer they nursed, the less apt they were to develop the disease in the 15 years after giving birth; the odds fell about 14 to 15 percent for each additional year spent breastfeeding.
Research has turned up tantalizing new clues suggesting pregnancy may provide women’s bodies with a kind of built-in repair kit. While it’s been known for some time that cells from the fetus pass into the mother’s bloodstream during pregnancy and remain there for years, scientists have more recently discovered that these fetal cells seem to be stem cells (a kind of universal spare-part cell), and that they can sometimes help heal damaged organs.
Diana Bianchi, a professor of paediatrics, obstetrics and gynaecology at Tufts University in Boston, describes a case where a woman infected with hepatitis C remained healthy even after she quit taking antiviral medications. When doctors investigated, they discovered something unexpected. “There were thousands of male cells in this woman’s liver,” Bianchi says. DNA fingerprinting traced the source back to a pregnancy 19 years earlier. Since then, animal studies have confirmed that lingering fetal cells seem to help reverse a type of liver poisoning. Pregnancy really is the gift that keeps on giving!
You don’t need to give birth to reap the health benefits babies bring. For instance, some adoptive mothers are opting to breastfeed (via months of pumping prior to getting their babies), which presumably offers some protection against breast and ovarian cancer. And animal research indicates that most of motherhood’s brain-boosting power is due to the mental stimulation of caring for kids. Craig Kinsley, a professor of neuroscience at the University of Richmond in Virgina, and his colleagues tested the memory skills of three groups of female rats: mothers, virgins and foster mothers. The exercise involved predicting where Froot Loops (a rat treat) would be hidden in a maze, based on earlier experience. While the biological mothers placed slightly ahead of the foster moms, both groups performed the task much more efficiently than females with no mothering experience. Consequently, the scientists believe the mental exercise involved in caring for pups honed the mama rats’ mental skills. Just a little something to keep in mind when you’re racing through those grocery aisles picking up cereal!