A friend once told me that she cries a little every month during her period — not because of raging hormones, but because it’s one less egg she’ll have when she’s actually trying to get pregnant.
For women who know they want to have kids, that’s a pretty grim thought, but it turns out to be even worse than that: We lose hundreds or even a thousand eggs per month through a process that’s like programmed cell death, says Owen Davis, MD, president of the American Society for Reproductive Medicine (ASRM). And even if you’re preventing ovulation with the pill or an IUD, those unreleased eggs don’t stick around — they die.
This massive monthly die-off is why women can go from having 1 or 2 million healthy eggs on the day they’re born to about 1,000 non-functioning ones at menopause, says Dr. Davis, who’s also the associate director of the IVF Program at the Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine at Weill Cornell Medical College in New York City.
Maybe you’ve heard some of these scary-sounding stats like how, at puberty, women already have less than 500,000 eggs and the number continues to drop before decreasing sharply after age 35. This can really freak out people who know they want to be parents (or are still unsure), especially since more and more couples and single women are having kids later in life. (Women in their late 30s and beyond can and do get pregnant without assisted reproductive technology, or ART, but it’s better not to wait until you’re, say, 45.)
A woman’s egg count – which is roughly synonymous with her “biological clock” — is a figure that reproductive endocrinologists have been able to estimate for the past 40 years with certain hormone tests. Knowing a woman’s ovarian reserve, as it’s called, can help fertility doctors counsel their patients on next steps as they plan their families, and even which ovulation-stimulating hormones to try.
Now, anyone can buy a test at the drugstore or online that will assess these hormone levels, and they could do it before they even start trying to get pregnant, conceivably for reassurance. But should they?
What is an ovarian reserve test?
It’s important to understand what ovarian reserve tests are actually looking at, Dr. Davis says. A fertility doctor can test a woman’s follicle stimulating hormone (FSH) or anti-mullerian hormone (AMH) — both of which can give a sense of how many eggs a woman’s ovaries might produce when given IVF drugs, but neither determines exactly how many eggs she has or, crucially, what condition those eggs are in.
The tests would either come back with a normal range or an abnormal one and therein lies one problem: a 25-year-old and a 45-year-old could both have an abnormal ovarian reserve, but the younger woman’s pregnancy chances are still better than the older woman’s because her eggs are younger, too. As Dr. Davis put it, “Aging of the eggs affects the quality no matter how many one has.” So it’s not very useful for saying you will or you won’t get pregnant.
Another snag: getting a normal FSH result doesn’t mean a damn thing. “A woman with a bad FSH one month could have a completely normal FSH the next month,” he says. “And in fact, women with the worst ovarian reserve tend to have the most variability from month to month in their FSH level.”
“I don’t think you can substitute that for an appropriate evaluation,” Dr. Davis says. “If a person’s over 35 and they’ve been trying for eight months or a year to get pregnant, they shouldn’t do a home sperm test or a home FSH test and say ‘I’m fine.’ It could be misleading.”
But one way a home test is useful, at least theoretically, is if someone who wants to have a family gets an abnormal test result, it gives them a sense of urgency. “If you have a home test that raises a red flag, don’t freak out, but do go directly to a reproductive specialist and let them do whatever further assessments are necessary and counsel you based on your entire health history as to what your best chances would be to have your family as complete as you want to make it.”
On the other hand, AMH levels vary less from month to month and you don’t have to do the test on a certain day of the cycle like with FSH. The AMH test is now more common in Dr. Davis’s practice than the alternative, but it also has its issues, including the possibility of different results depending on how a lab processes it.
What he thinks is more useful than either blood test is actually looking at the ovaries and counting the number of visible eggs during a routine vaginal ultrasound. (Doctors do this in an initial infertility exam to look for structural problems that could affect pregnancy, like fibroids and polyps.) Each month, some of the follicles, the structures that hold the eggs, fill with fluid and they’re big enough to see. This number correlates to the total number of egg-containing follicles a woman has.
Tests like these could have devastating results for a very small group of women who lose their eggs faster than usual, says Samantha Butts, MD, associate professor of obstetrics and gynecology at the Hospital of the University of Pennsylvania. Women who have irregular or missing periods and menopausal symptoms like hot flashes could have a condition known as premature ovarian failure or primary ovarian insufficiency, which affects one percent of women. Some women with POF/POI will report that their mothers went into menopause earlier than the average age of 51. There’s about a 5 percent chance that these women can get pregnant without alternative forms of fertility treatments like using donor eggs or donor embryos.
Remember to think beyond eggs
While it’s a good thing overall for women to think about factors that might impact their reproductive chances, ovarian issues like low egg count or older eggs aren’t the only causes of infertility, says Dr. Butts, who also serves as the chair of the American College of Obstetricians and Gynecologists gynecologic practice subcommittee on reproductive endocrinology.
Abnormalities in the uterus and fallopian tubes can also hinder your chances, as can untreated STDs like chlamydia, which can lead to fallopian-tube-blocking pelvic inflammatory disease, and a man’s sperm count and quality, she says. In fact, infertility affects women and men equally — let that sink in for a moment. About a third of infertility cases are the result of issues in the woman, a third can be attributed to men, and the remaining 40 percent are either a combination of both or, sadly, can’t be explained, according to Resolve: The National Infertility Association.
“I understand the desire to characterize [fertility] with a test, but I also think it’s such a sophisticated, complicated thing to capture that it needs to be treated as such,” Dr. Butts says.
Dr. Davis agrees. “You have to take a few different data points and put them together, plus the patient’s family history, plus whether she’s been pregnant before, and her age, to really come up with ‘how aggressive should we be how soon?’ If you just take an FSH level in a vacuum or just take and AMH level in a vacuum, even if you’re a clinician sending it off to a trusted lab, that’s probably not enough and it could be misleading one way or the other.”
And though you can’t control whether you’re going to have health conditions or abnormalities that affect fertility, there is something you can do to make sure you’re not robbed of reproductive years: Throw out the freaking cigarettes. Both doctors agreed that smokers go into menopause sooner than non-smokers do, so do yourself a favor and quit already.
When to call for backup
Let’s say you’re ready to start having kids: Should you do a home test or call a fertility doctor as soon as you stop using birth control? Maybe, if you’re part of a group that’s at higher risk for problems.
The ASRM recommends that women with health conditions that affect ovulation and menstruation, like endometriosis that required surgery or polycystic ovary syndrome (PCOS), talk to a specialist before they get going.
The same goes for women who are going to be treated for cancer, since chemotherapy and radiation can affect ovarian function (in that case, some insurers cover certain types of assisted reproductive technology, but most do not cover egg freezing or IVF), and for couples where the male partner has a reason to suspect sperm problems thanks to a testicular injury or undescended testes. Dr. Davis adds that if you’re a woman in your 40s it’s probably a good idea to get evaluated first.
If none of these situations apply to you, the latest advice is that women under 35 should wait a year before calling for backup and women over 35 should do so after six months. (Though if we stick with Dr. Davis’s recommendation, the latter group is really women ages 35 to 39.)
But what about the women who still aren’t sure if they want to have children but are extremely aware that they’re running out of time to decide? Dr. Butts sees these patients in her practice, too, and they have long talks about options, including egg freezing. Some go for it and others decide it’s not right for them, but having that discussion in the first place is key.