How PCOS Affects Ovarian Reserve and What This Means for Fertility

Polycystic ovary syndrome (PCOS) is a common health condition that affects approximately 1 in 10 women of childbearing age, according to the Office on Women's Health in the U.S. Department of Health and Human Services (HHS).

"Up to 70 percent of individuals don't realize they have PCOS because they haven't been diagnosed with the condition," stated Lynae Brayboy, M.D., an OB-GYN and chief medical officer at Clue by Biowink, a period-tracking app headquartered in Berlin.

The condition is characterized by an imbalance of hormones, specifically, elevated levels of androgens, the male sex hormone, which can lead to irregular periods and, therefore, irregular ovulation when an egg releases from the ovaries. Without regular ovulation, it can be difficult to become pregnant.

This is why PCOS is one of the most common causes of infertility in women, according to HHS. Many women with PCOS need help getting pregnant, and the condition creates unique considerations when seeking fertility treatment. Some scientists speculate that women with PCOS may actually have some advantages over those with "normal" reproductive function. So far, however, the scientific studies have led to mixed conclusions.

Research is ongoing, but here's what scientists know so far.

PCOS patients often have higher ovarian reserve

One of the factors you may have heard discussed in regard to fertility is the importance of ovarian reserve, the total number of healthy, immature eggs in the ovaries, according to the National Cancer Institute. The number of eggs decreases as a woman ages, which lowers fertility and the chance of becoming pregnant.

Ovulation doesn't occur regularly—or sometimes at all—in women with PCOS, so they often retain more eggs in their ovaries than women without the disease and, therefore, have a higher ovarian reserve than women with "normal" reproductive function.

"The rate of follicle loss per year was significantly slower in PCOS women compared with that in non-PCOS women," according to a 2013 study published in the medical journal Reproductive Biomedicine Online.

"Patients with PCOS have a high ovarian reserve," said Dan Nayot, M.D., a reproductive endocrinologist and the medical director at the Fertility Partners, which has multiple locations in Canada. "In fact, one of the defining features of PCOS is having lots of follicles in the ovaries."

Polycystic ovary syndrome gets its name because this condition can cause cysts—small, fluid-filled sacs—to accumulate on the ovaries. These cysts are called follicles and they contain immature eggs (oocytes).

In a normal menstrual cycle, an oocyte breaks free from its follicle during ovulation and travels down a fallopian tube and into the uterus. With PCOS, however, the egg doesn't break free and stays contained in its follicle. Without regular ovulation, follicles filled with oocytes continue to build up around the ovaries.

What does this mean for fertility?

A higher egg count isn't always a good thing

"Although women with PCOS have a higher egg count, this isn't always a good thing," explained Matthew Macer, M.D., a specialist in reproductive endocrinology and infertility and medical director at Halo Fertility in Los Angeles.

"For most women with PCOS, their ovaries are not able to select any of their eggs to grow and ovulate," Macer continued. "So, although they may have many of them, if the body isn't growing and ovulating, it can be really tough to [get] pregnant without a little help from a specialist."

"Patients with PCOS have more visible follicles on ultrasound," added Sam Najmabadi, M.D., an OB-GYN and reproductive endocrinologist at the Center for Reproductive Health & Gynecology in Los Angeles.

"This does not mean the patient is more fertile," Najmabadi cautioned. "It actually causes infertility by not allowing the normal process of follicle development to continue and allow eggs to be released for possible fertilization."

Does PCOS lead to a longer reproductive window?

One aspect being researched is whether women with PCOS might have a longer reproductive life span because of their higher egg count and the fact that PCOS symptoms tend to decrease over time, meaning ovulation can become more regular with age. With regular ovulation comes a higher likelihood of becoming pregnant.

However, the research has yielded differing conclusions.

"Women with PCOS display sustained fertility with advancing age as compared with infertile eumenorrheic women," stated the authors of a 2011 study published in the medical journal Human Reproduction. Eumenorrhea refers to a healthy, normal menstrual period.

In the study, 1,000 women with infertility, ages 22 to 41, were included: 500 diagnosed with PCOS and 500 with tubal-related infertility. The researchers found the oocyte count and live birth rates remained stable in the women with PCOS regardless of age, while these factors decreased with age for the women without PCOS.

However, a large 2013 study published in the journal Fertility and Sterility that examined more than 42,000 cycles determined that while women with PCOS have more oocytes, this does not necessarily lead to increased birth rates.

"Despite a higher oocyte yield in all age groups, women with PCOS over age 40 had similar clinical pregnancy and live-birth rates compared with women with tubal factor infertility," the study authors stated. "These findings suggest that the reproductive window may not be extended in PCOS and that patients with infertility should be treated in a timely manner despite indicators of high ovarian reserve."

A 2019 study in Frontiers in Endocrinology found women with PCOS show a slower decline in fertility and better oocyte retrieval, which may lead to better opportunities for egg transplant during in vitro fertilization (IVF).

"However, advanced age still plays a critical role in the ultimate success of a single stimulation cycle in PCOS patients," the authors cautioned.

Egg quantity does not equal egg quality

One of the reasons the reproductive window may not be better for women with PCOS despite their higher ovarian reserve is the difference between egg quantity and egg quality.

"One very important principle in reproductive medicine is that egg quantity and egg quality are independent variables," Nayot explained.

Egg quantity is measured by ovarian reserve testing, which includes bloodwork that measures the levels of follicle-stimulating hormone (FSH) and anti-Müllerian hormone (AMH), and a pelvic ultrasound to measure the number of follicles in the ovaries (antral follicle count).

"Unfortunately, there are no tests for egg quality," Nayot continued.

In other words, although a woman with PCOS has more eggs—a higher ovarian reserve—the condition of those eggs cannot be tested.

Instead, quality is assumed based on the woman's age. Women are born with a set number of eggs, and both the quantity and quality of those eggs decrease over time.

"While women with PCOS might have a longer reproductive life span prior to menopause, it doesn't mean their oocyte quality—potential to be fertilized and develop into an embryo that creates a pregnancy—is better when they have assisted reproduction, such as in vitro fertilization," Brayboy cautioned.

Why ovulation regulates with age for people with PCOS

"As women get older, the baseline FSH levels rise," Nayot explained. "In PCOS, one of the main issues is the FSH to LH [luteinizing hormone] ratio is not in balance. So as women get older and their baseline FSH rises, some PCOS patients begin to ovulate regularly; the FSH to LH ratio normalizes.

"There might be several reasons why someone with PCOS isn't conceiving," Nayot continued. "But if the underlying issue is that they don't ovulate, and then as they age they begin to ovulate—irregular cycles that evolve into regular cycles—they very well might conceive on their own. However, it's important to remember that as women get older, their egg quality declines, which translates to a lower chance of success per egg."

"Age for a patient with PCOS becomes a double-edged sword," explained Karenne Fru, M.D., Ph.D., an OB-GYN and fertility specialist with Oma Fertility in Atlanta. "On the one hand, enough ovarian follicles have died off over the course of normal aging that she may start spontaneously ovulating. On the other hand, older eggs less efficiently convert into embryos. So while there is more opportunity to get pregnant, these opportunities are riddled with increased risk for chromosomal abnormalities or oocyte dysfunction that fails to establish a pregnancy."

"The truth is that we, the scientific community, don't know enough about reproductive aging for all people with ovaries," Brayboy said. "There is data to suggest that the androgens that are elevated in women with PCOS do decrease, and they enter menopause later. However, PCOS is not immune to the increased risks of oocyte aneuploidy [abnormality] that occur as people with ovaries age.

"So, in summary, women with PCOS may start to ovulate more regularly as they age, but this does not mean they have an advantage," Brayboy continued. "More clinical research is needed to document the natural progression of PCOS with aging."

Treatment options for PCOS

Medication to regulate ovulation is often a very effective treatment for people with PCOS, Macer explained.

"They have a surplus of eggs, we just need to use them," he said.

Some of the eggs may be slightly lower quality, but generally, they are still very healthy. However, because other factors may be at play in addition to irregular ovulation, more advanced treatment, such as IVF, may be needed.

"There are numerous reasons why someone with PCOS might have difficulty conceiving. The most common reason is a hormonal imbalance that prevents them from ovulating regularly, or releasing an egg every month, but there are others," Nayot explained. "Many, but not all, patients with PCOS have other metabolic issues, such as obesity and insulin resistance. It's best to optimize all variables and not just focus on fertility."

Najmabadi suggested addressing the following lifestyle issues to optimize pregnancy success:

• Weight loss
• Increased physical activity
• A healthy, low-carbohydrate diet
• Oral medication, such as metformin

"The good news is we can do many less invasive lifestyle changes to help these patients," Najmabadi said. "Many may end up needing more aggressive treatments, but overall, there is hope and light at the end of the tunnel."

The bottom line

If you have PCOS and want to have children, don't wait to speak to a fertility specialist about the unique considerations you need to be aware of as you determine the right timing for a pregnancy.

"Early intervention is needed to provoke ovulation in PCOS patients desiring pregnancy," Fru advised.

If you've been trying for 12 months to get pregnant without success, it's time to seek assistance.

Brayboy also stressed the importance of tracking your period.

"Reproductive endocrinologists will take a complete health history, including menstrual history, which includes when your periods started, when your last period was and how often they come and how long you bleed," she explained. "These questions are usually very difficult for people to answer unless they are tracking."

If you're not ovulating regularly, a solution to infertility may be as simple as medication to help you ovulate. If your doctor determines diet and lifestyle factors are also affecting your fertility, then additional changes may be needed.

"I always advise patients to advocate for themselves," Nayot said. "They should have a good understanding of how their diagnosis was made, how it impacts their fertility and what treatment options they can consider, which includes the chance of success, costs, logistics and risks."