Fertility is like most aspects of medicine — it’s rarely discussed until a problem arises. But as women wait longer to start families, sometimes those discussions come too late.

Modern Fertility is one of a growing number of biotech companies that want to start the conversation sooner. It and other startups in the “femtech” field — technology companies that offer products around women’s reproductive health, such as period-tracking apps, birth control subscription services, and egg-freezing boutiques — are providing women with access to private fertility services that used to be solely within the purview of doctors. Their goal, the companies say, is to help women be better informed and more proactive about their health.

“There is a lot of confusion when women are trying to conceive,” says Afton Vechery, co-founder and CEO of Modern Fertility. “It’s a black box, and they are looking for more data to understand what’s going on.”

The rise of femtech startups — which have raised more than $1 billion since 2014 and are projected to be a $50 billion industry by 2025 — has coincided with a declining U.S. birth rate, in part due to women waiting longer to start trying to conceive. The U.S. birth rate dropped in 2017 in every age group except women over 40, and women ages 30 to 34 now have a higher birth rate than women in their twenties. As women continue to delay having children, more are turning to assisted reproductive technology, such as egg freezing and in vitro fertilization. Like other direct-to-consumer health care startups, femtech companies view this space as being ripe for major disruption — and money.

Modern Fertility has carved out a diagnostic niche. The company offers an at-home testing kit for up to eight different hormones, including the three most important ones related to fertility: anti-Müllerian hormone (AMH), follicle-stimulating hormone (FSH), and estradiol.

As an unmarried woman in my early thirties who would like to have kids someday, I was curious about my own numbers, so I ordered a test from Modern Fertility. The kit arrived in the mail in the smooth, matte white packaging popularized by Apple, with a chic but discreet logo on the front. Following the instructions, I laid out all the materials on my kitchen table, washed and sterilized my hands, and punctured the tip of my left ring finger. I massaged my forearm and held my hand over the collection card, watching the blood slowly drop onto a small target square. After waiting 90 minutes for the blood to dry, I popped the card into the special packaging Modern Fertility provides and mailed it back.

Modern Fertility says that knowing your AMH, FSH, and estradiol levels can give you insight into your ovarian reserve, egg-freezing and IVF options, and even your timeline for menopause. AMH, or anti-Müllerian hormone, is produced by egg follicles in the ovaries and provides a rough estimate of ovarian reserve — the number of eggs waiting in the wings. The more follicles left, the higher the hormone levels. AMH levels are highest in puberty and decline as women lose eggs as they age. When a woman reaches menopause, her AMH levels drop to zero, because there are no more egg follicles left.

FSH, or follicle-stimulating hormone, is secreted by the pituitary gland and travels through the bloodstream to the ovaries, where it tells the follicles to release their eggs. When a woman has a high egg count, only a little bit of FSH is needed to trigger ovulation, but as egg reserves become depleted, the brain has to produce more FSH to get the same result. In general, higher FSH levels are thought to coincide with lower egg reserve.

However, estradiol, an estrogen steroid released by the ovaries, can suppress FSH production, artificially lowering test results. To get an accurate read on FSH, doctors recommend testing for the hormones in tandem and only during the first few days of a woman’s monthly cycle, when estradiol levels are low. Birth control also messes with FSH and estradiol, so a woman using a hormonal contraceptive — birth control pills, implants, and some intrauterine devices (IUD) — won’t be administered those two tests.

Lynn Westphal, an emeritus professor of obstetrics and gynecology at Stanford University, says that while the hormones Modern Fertility tests for can help evaluate egg reserve, the results are far from definitive for a person’s fertility. In fact, one recent study showed no connection between AMH and FSH levels and natural conception rates in 750 women over the age of 30.

AMH is, however, a strong predictor of how well a woman will respond to fertility drugs if she undergoes IVF or egg freezing. “When we see that the numbers are in the range where we expect them to be, then that’s reassuring in terms of ovarian function,” Westphal says. “But it’s not telling someone their overall fertility, because there are so many factors involved.”

“It takes an egg, a sperm, and a uterus to have a pregnancy. We focus on ovarian function because we know that’s the one thing that clearly changes over time.”

At my doctor’s office, on a bare-bones insurance plan with a high deductible, a single elective test for AMH paid for out of pocket cost $50.

I use a hormonal IUD for birth control, so my Modern Fertility test included only AMH, which isn’t influenced by hormonal contraceptives. Despite that, I was still charged the full $159 for the test. Modern Fertility says that’s because I also gained access to its other offerings: a one-on-one consult with a fertility nurse, the company’s weekly webinar to review results, and an active Slack channel of other women who’ve taken the test.

One of the company’s selling points is that its test is cheaper than going through your doctor or a fertility clinic. On its website, Modern Fertility claims a hormone panel can cost $1,500—a number Vechery also cited in our conversation based on her experience at a fertility clinic. At my doctor’s office, on a bare-bones insurance plan with a high deductible, a single elective test for AMH paid for out of pocket cost $50.

Less than a week after sending in the test, I received a notification in my inbox that my results were ready. According to Modern Fertility, my AMH levels fell within the normal range for my age. I got a different number from the AMH test I took the following week through a venipuncture blood draw at my OB-GYN, which placed me in the low-to-normal category.

The discrepancy in my results doesn’t necessarily mean that one of the tests is inaccurate. Westphal says it’s “not unusual” to see variations from lab to lab, and it’s “not as big of a difference as it may seem.” Modern Fertility recently published a peer-reviewed paper showing a tight correlation between fingerstick and traditional venipuncture hormone tests. But the difference between the tests does drive home the fact that I shouldn’t place too much weight on either number.

Even if the results were consistent, the tests don’t tell me very much about my odds of getting pregnant. Despite the wealth of scientific information Modern Fertility provides to explain the results and put them in context for my age — way more than I received from my doctor and, to me, the company’s most useful offering — a single test can’t tell me how many eggs I have left, how quickly they’re falling, or the quality of those that remain. It provides no information about the state of my uterus and, of course, nothing about that other half of the equation — my partner.

“The talk of a fertility test is a bit problematic, because it’s not really a fertility test—it’s an egg quantity test,” says Alan Penzias, a reproductive endocrinologist at fertility clinic Boston IVF and an associate professor of obstetrics, gynecology, and reproductive biology at Harvard Medical School. “Egg quantity may have some bearing on fertility treatment outcomes when you’re trying to do fertility therapy, but it may be completely unrelated to whether or not somebody gets pregnant.”

“If they say, ‘Tell me my egg quality,’ I say, ‘Show me your driver’s license.’ Because that’s the best I can do.”

The other major factor is egg quality — the likelihood that an egg will be successfully inseminated and develop into a healthy embryo. Quality, like quantity, declines with age, but scientists have no way to measure it.

“If somebody says to me, ‘Tell me what my egg quantity is,’ I say, ‘Well, show me your blood,’… and with some caveats around that, I’ll give you a rough categorization,” Penzias says. “If they say, ‘Tell me my egg quality,’ I say, ‘Show me your driver’s license.’ Because that’s the best I can do, the closest I can get to egg quality.”

Penzias’ concern with private tests provided without consultation from a doctor is that the results could either unnecessarily scare or falsely reassure women. A recent New Republic article asked whether the rapidly proliferating femtech industry is “alleviating women’s anxieties or exploiting them.” There are perhaps no issues more fraught or more primal than personal health and reproduction. Companies like Modern Fertility want you to believe that they can give you data-driven insights into these topics, like a Fitbit for your ovaries. A friend of mine described these products more accurately, I think, as an Ouija board.

But Westphal, who was recently named chief medical officer of the boutique fertility clinic Kindbody, says more information is almost always better. “I think it’s always good to be educated and have information. Anything that makes women think carefully about when they want to have their children, I think it’s good to have that conversation early, because I see too many women who are misinformed about their fertility.”

Femtech may have become a fast-growing industry because it’s a genuinely needed one. There has long been a dearth of knowledge and investment in women’s health, and while companies like Modern Fertility are capitalizing on that gap, they’re also filling it with data.

Vechery, who has worked in health care private equity evaluating IVF clinics, as well as at personalized medicine startups like 23andMe, says her own expensive experience getting her hormones tested and her friends’ subsequent questions about the process inspired her to start the company.

“A core part of why we started Modern Fertility was to make this type of testing and information as accessible as we possibly could,” Vechery says. “We launched [this company] because we wanted this resource. We wanted this for ourselves, our friends, our sisters, our family members.”

Personally, I don’t think the company’s tests provided me with that much information, although maybe I feel that way because my numbers were relatively normal. I do have some peace of mind that I don’t need to start thinking about having children tomorrow. But ask me again in nine months, when Modern Fertility suggests I spend another $159 to recheck my levels to see how my numbers have changed, and maybe my answer will be different.