The female reproductive system has been regarded for thousands of years as a source of never-ending mystery (the ancient Greeks reportedly believed that the uterus could just up and move around whenever it wanted) while simultaneously being something to just deal with (*anyone who’s ever had a period in their life nods along vigorously*).

Even today, certain female reproductive conditions remain understudied and misunderstood. Take pregnancy: A recent Washington Post deep dive explored the fact that pregnant women have consistently been left out of clinical trials. This means that we don’t know how certain medications impact pregnant people or their babies; we don’t know much about the placenta and how it forms; it means, in fact, that we don’t know much at all.

The knowledge gap extends to one’s ability to get pregnant, too. A small 2016 survey of women found that only one in three participants knew that female fertility declines after age 35; another 2017 survey found that most respondents over-estimated the pregnancy chances of women over 40. And a Portuguese survey of over 2000 people found that only 18 percent of participants had brought up fertility problems with their doctor (even though 95 percent wanted to have kids someday).

The issue is not just that female fertility remains a frustratingly confounding riddle—it’s that your reproductive system can tell you so much more about your health than whether or not you can get pregnant. And our ignorance of how it works is holding many women back from better understanding their health.

Your hormones affect more than your period

The female reproductive system functions via a delicate balance of hormones, including estrogen, testosterone, progesterone, luteinizing hormone, and follicle-stimulating hormone. These hormones are directly involved in your menstrual cycle, egg production, ovulation, and basically every other function of these organs. They fluctuate throughout the month during your cycle, as well as other key moments: the onset of puberty, during and immediately after pregnancy, and menopause. (Men experience minor hormonal fluctuations as well, just not to the same degree as women.) The healthy functioning of your reproductive system, including hormonal levels, is crucial for pregnancy; if women are having trouble getting pregnant, doctors generally perform a variety of hormone tests to understand what’s going on.

All of that has been known for a while. But most experts know now that these sex hormones have so much more to do with your overall health than previously understood. Norbert Gleicher, MD, FACOG, FACS, an OB/GYN at the Center for Human Reproduction in New York, describes it this way: “As recently as 15, 20 years ago, we believed that every gene in our body only had one function in the body. Today we understand that every gene has multiple functions. The same thing applies to hormones.”

“Our hormones go way beyond just our reproductive capacity or our pain and our periods—they impact everything from brain function to metabolism; to immune function and stress response.” —Alisa Vitti, HHC, founder and CEO of Flo Living

“Our hormones go way beyond just our reproductive capacity or our pain and our periods—they impact everything from brain function to metabolism; to immune function and stress response,” adds Well+Good Council member Alisa Vitti, HHC, founder and CEO of Flo Living, and author of Woman Code: Perfect Your Cycle, Amplify Your Fertility, Supercharge Your Sex Drive, and Become a Power Source. In other words, your sex hormones work in harmony with your brain and the rest of your body to make sure every system in your body runs in tip-top shape.

However, it’s a delicate ballet, and if one hormone shifts suddenly, you’ll feel the effects. For example, estrogen has a “direct impact on dopamine and serotonin,” says Jessica Shepherd, MD, a gynecologist and medical advisor for Rory, a healthcare platform for women. If your levels dip too low, you may find yourself feeling depressed. Same with testosterone—while the levels in women are generally lower than they are in men, Dr. Shepherd says too little can cause fatigue, fogginess, and a decreased sex drive. On the flip side, if your testosterone levels are too high, that could lead to polycystic ovarian syndrome (PCOS), symptoms of which can include acne, hair loss, stubborn weight gain, infertility, and increased risk of diabetes. Some experts even warn that the popular ketogenic diet could put undue stress on women’s hormonal systems, potentially causing unwanted weight gain, missed periods, acne, and even prediabetes.

Dr. Shepherd says some research also suggests that the major hormonal shift women experience during menopause can lead to increased irritability, poor concentration, memory difficulties, low self-esteem, poor sleep, and weight gain. There could be bigger consequences of these more dramatic hormonal fluctuations—as explored in a New York magazine feature about menopausal schizophrenia—but current science really explains only the tip of the iceberg.

The enduring mystery of hormones

A lot of our collective question marks about how hormones can affect the body comes down to the fact that most research is done on men and postmenopausal women, Vitti says. People can get squeamish about the idea of potentially harming pregnant women and their babies—so much so that in 1977, the Food and Drug Administration (FDA) banned pregnant and or “potentially pregnant” women from all clinical trials. (That decision wasn’t reversed until 1993—meaning there were 16 years of lost research that could have happened on women.) For a long time, women’s hormonal fluctuations were also considered too “complex” and it was thought that they’d basically skew the results of any study. Vitti stresses that this is a completely solvable problem. “It seems like more of a lazy oversight than anything,” she says. All of this means that we don’t have a clear concept about how our unique hormonal makeup can impact (or be impacted by) certain eating plans, drugs, and types of physical activity.

“Women’s hormonal changes don’t have the same urgency for society or the medical community as curing cancer or another major disease.” —Norbert Gleicher, MD, FAAOG

Dr. Shepherd adds that when it comes to research money, certain hormonal health conditions—such as endometriosis or PCOS—aren’t at the top of the priorities list, even though they can have major impacts on a person’s health. “Who’s going to conduct a study if there are no funds?” she says. Long-held gender biases come into play when setting those priorities, adds Dr. Gleicher. He says that hormonal fluctuations are considered just a normal part of being a woman and thus “don’t have the same urgency for society or the medical community as curing cancer or another major disease,” that they should.

However, Dr. Shepherd says that this lack of knowledge is a multi-layer problem. Many of those same hormonal conditions can mimic other disorders, making them hard to diagnose. Additionally, many women don’t find out that they have endo or PCOS until they try—and have trouble—getting pregnant, but there’s no easy way to find them earlier unless a person proactively seeks out help. (Still, it stands to reason that researching those conditions could help address some of those issues with diagnosis.)

“You have to think of medicine and the way we treat people in regards to something that might come up later,” Dr. Shepherd says. “We can’t screen everyone, and say, ‘Are you at risk for this, which might make you infertile, even if you don’t have any complaints about it now?’ It wouldn’t be cost-effective.” Unfortunately, that also means that women often don’t have the knowledge they need to fully understand their own health—or in the case of childbearing, to plan their lives. Think of it this way: a person who intends to have children might make different decisions about their healthcare and family planning (like egg freezing, holistic treatments, etc.) if they knew in their 20’s that they had a hormonal imbalance. But if they don’t learn about fertility issues until after a year of trying and failing to conceive (the standard recommendation for infertile couples), that can be heartbreaking for people who thought they had more time or didn’t realize how hard it would be to get pregnant.

Redefining fertility

Right now, Dr. Shepherd says doctors usually initiate a conversation about fertility with patients when they’re around 32 to 34—giving people who may want children some buffer time before fertility starts to decline in the mid- to late- thirties. But Vitti argues we should start the conversation even earlier, noting that if we focused on the “real science” of hormonal patterns, they’d be a “non-thing, instead of this falling off a cliff at puberty, which is so damaging to girls.” Changing the conversation around hormones could change the conversation about fertility, she says, because the more knowledge women have about their own hormonal cycles, the more attuned they’d be to their fertility and overall health.

Thankfully, technology and some health practitioners have started to catch on to the importance of hormones. Companies like Parsley Health offer hormonal testing to their clients (normally only available through an infertility specialist), and startups from Vitti’s FloLiving to Everlywell offer at-home hormonal testing kits and support for people to take their metrics into their own hands. That’s on top of the latest generation of fertility-tracking apps and devices people can purchase over the counter. There are certainly downsides to these tools: at-home tests might not offer the same insight (or accuracy) that working with a hormone specialist would. And going to your doctor’s office and demanding hormone tests isn’t always an affordable option—they’re not always covered by health insurance and can cost hundreds of dollars out of pocket.

Still, thinking about hormones outside the scope of pregnancy and periods—and thinking about it sooner rather than later—can help empower people to have a deeper understanding of the factors that impact their health, whether or not they want children. “We can’t control a lot of things, but what we can do is focus on our own fertility, our own hormonal well-being, and make the best choices that we can with the choices that are in front of us,” Vitti says.

Is fertility genetic? It’s complicated, experts say. And meet the doula who sees her work as part of a larger social mission.