Women make up 52% of the population.

So when scientists are determining the proper dosage for a medicine, you might assume that at least half the data used is collected from women. But historically that's not true.

Relatively new requirements from the National Institutes of Health (NIH) are trying to change that.

Since 2007, the NIH has required about half of all clinical trial participants in NIH-supported research to be women.

A 2016 update requires sex to be considered as a biological variable. That means researchers should include sex differences when designing their studies, analyzing their data, and publishing their findings.

Not only have women been underrepresented in clinical trials—in basic scientific research the animals, and even the cells, have been almost exclusively male.

"That's happened in part because female physiology is more complicated," says Dr. Sarah Kilpatrick, chair of the Department of Obstetrics and Gynecology.

"It's also been because of the oversimplified expectation that it wouldn't matter. Now we understand that women aren't simply smaller men."

Identifying and acknowledging sex differences is just the beginning.

Translating that knowledge into medical care and guidelines that recognize the physiological differences in women comes next.

"The most immediate approach to personalized medicine is to recognize if your patient is a man or a woman," says Dr. C. Noel Bairey Merz, director of the Barbra Streisand Women's Heart Center. "You don't need a DNA test to do it."

Establishing different guidelines for treating men and women, whether it applies to medication dosages or recalibrating the sensitivity of blood tests, is the kind of change we need.

An example Dr. Bairey Merz points to are the tests used to determine if someone has had a heart attack.

One way to test if someone has had a heart attack is to measure the level of troponin in the blood. But the troponin levels in women who have had heart attacks can be 15-20% lower than those in men who had heart attacks.

"If you use male standards, you miss 20% of heart attacks in women," she says.

Studying sex differences is another way to improve healthcare for women. With that focus in mind, a group of Cedars-Sinai doctors and researchers recently formed the Center for Research in Women's Health and Sex Differences (CREWHS).

Their goal is to expand studies on sex differences and women's health disparities. They're also working to educate doctors, nurses, researchers, and the community on sex differences in biology and diseases, and how that affects delivery of healthcare.

The group is holding its inaugural symposium on May 14, when researchers will share their work highlighting gender differences and women's health.

A small step every woman can take to improve their health and raise awareness about gender differences in medicine: Ask your doctor about concerns you have.

Whether it's specific to a health condition or about medication dosing, speak up.

"We don't have all the answers yet," Dr. Kilpatrick says. "But if we don't ask, we'll never get them."