Can Ovarian Reserve Tests Predict Fertility?

According to a recent study published in the Journal of the American Medical Association (JAMA), the number of remaining eggs in your ovaries (ovarian reserve)—as revealed through blood and urine tests—don’t necessarily predict fertility.¹ So what exactly do these tests reveal and what’s the best way to make use of the study results?

What AMH, FSH, and Inhibin B Tests Can Tell Us
Levels of certain hormones change with aging and can be useful indicators of ovarian reserve.

Antimüllerian hormone (AMH). Produced directly by early-stage ovarian follicles, AMH predicts ovarian reserve, a measure of egg yields at in vitro fertilization (IVF). High levels of AMH are favorable, while low levels indicate decreased ovarian reserve.² Researchers have also shown an association between levels of AMH and the time until menopause.

Follicle-stimulating hormone (FSH). Secreted by the pituitary gland, this hormone is highest just before ovulation. Higher-than-normal levels may indicate low ovarian reserve or low egg numbers.³

Inhibin B. A protein secreted by the group of small, resting follicles in the ovary, this hormone may also help assess ovarian reserve. The higher the levels of inhibin B, the greater number of follicles present in the ovary, theoretically increasing the chances of pregnancy.⁴

Results of the JAMA Study
Some individuals have promoted or used tests for ovarian reserve as a way to predict reproductive potential. But until recently, evidence linking the two was lacking. Researchers recently explored this potential link with a prospective study following 750 women, ages 30 to 44, from 2008 to March 2016. Recruited from the Raleigh-Durham, North Carolina area, the women had no history of infertility and had been trying to conceive for 3 or fewer months.

The women provided blood samples for AMH, FSH, and inhibin B, as well as urinary levels of FSH.

The researchers compared these results with the ability to conceive within a given menstrual cycle, as well as cumulative results after 6 or 12 cycles. They also took into account other factors that could affect the results, such as body mass index (BMI), age, race, and current smoking status.

These were the results of the study:

• Women with low AMH had a 65 percent chance of conceiving at 6 months (compared with 62 percent in women with normal levels) and 84 percent chance of conceiving at 12 months (compared with 75 percent in women with normal levels).
• Women with high blood FSH had a 63 percent chance of conceiving at 6 months (compared with 62 percent chance in women with normal levels) and a 82 percent chance of conceiving at 12 months (compared with 75 percent in women with normal levels.)
• Women with high urinary FSH had a 61 percent chance of conceiving at 6 months (compared with 62 percent chance in women with normal levels) and a 70 percent chance of conceiving at 12 months (compared with 76 percent in women with normal levels.)
• Women’s level of inhibin B was not associated with the chance of conceiving in any particular cycle.

The bottom line? Women with diminished ovarian reserve were just as likely to become pregnant as those with normal ovarian reserve. In other words, for each test there was no statistically significant difference between results for women with abnormal results and women with normal results. This included the chances of conceiving in a given cycle as well as cumulatively after 6 and 12 cycles.

The results were contrary to the researchers’ hypothesis and conflicted with those of earlier studies. Therefore, the researchers concluded that their findings don’t support use of AMH, FSH, or inhibin B tests to assess women’s natural fertility.

Making Sense of the Findings
First, egg health, the chance of an egg to produce a baby, is predicted by age, but not so much by egg number. Think of it this way: the number of eggs is the number of lottery tickets available to play the fertility game. Egg quality is the chance of each of those lottery tickets being a winner. You would love to have a bunch of lottery tickets to improve your odds, but an acceptable alternative is to have one good one. Numbers don’t matter that much.

Then, it’s important to know that women in this study, as well as their partners, did not have a history of infertility—so we can’t necessarily generalize the results to those who do have a history of infertility. In other words, it’s one thing to use these tests in women who have been struggling with infertility for some time. And it’s another to use them as fertility predictor tests in women with no history of infertility.

Third, the study only looked at outcomes for a positive pregnancy test, not delivery of a healthy child—the gold standard for fertility studies and the only outcome that truly matters. Poor-quality eggs may be fertilized—resulting in a positive pregnancy test—but may result in miscarriages and fewer live births, something this study did not evaluate.

Fourth, the study did not include enough numbers to adequately assess women with very low levels of AMH, which is more often seen in women who are getting closer to menopause.⁵

Ovarian reserve and fertility definitely decline with age, and that’s something women need to not lose sight of. However, this study suggests that there may not be a strict correlation between the number of remaining eggs and other factors affecting fertility, such as the quality of those eggs.

The authors of the study also suggest that AMH and FSH levels may affect the activation and recruitment of immature follicles in those with diminished ovarian reserve, thereby increasing the odds of becoming pregnant.⁵

Physicians at Pacific Fertility Center take all of these things into account when assessing the utility of these tests for their female patients—a group of women who are challenged by infertility, unlike the cohort in this study.

“These two groups should be evaluated differently,” said Eldon Schriock, MD. “We still believe these tests are important for our patients, but they are among many factors we take into consideration when evaluating a woman’s reproductive potential.”

Perhaps the biggest takeaway from this study? Don’t use good ovarian reserve as a reason to delay attempts to conceive. Although clinical and laboratory tests are useful for screening and assessing ovarian reserve, it’s important to combine them with other factors—such as monthly ovulation and age—to predict egg health and your ultimate ability to give birth to a healthy child.

Sources

1. Steiner AZ et al. JAMA.2017;318(14):1367–1376.
2. Pacific Fertility Center website: “Ovarian Reserve Predictors.” Available at: https://www.pacificfertilitycenter.com/blog/ovarian-reserve-predictors Accessed 11-15-17.
3. Pacific Fertility Center website: “Follicle Stimulating Hormone.” Available at: https://www.pacificfertilitycenter.com/glossary/follicle-stimulating-hormone Accessed 11-15-17.
4. Pacific Fertility Center website: “Limitations of Inhibin B Testing.” Available at: https://www.pacificfertilitycenter.com/blog/limitations-inhibin-b-testing Accessed 11-15-17.
5. Medscape: “Do Biomarkers Predict Fertility?” Available at: https://www.medscape.org/viewarticle/888069 Accessed 11-15-17.

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