PCO vs. PCOS: Understanding the Difference and What Each Means for Your Pregnancy

One of the hallmark symptoms of polycystic ovary syndrome (PCOS) is polycystic ovaries (PCO). 

What you might not know though is that not all women with PCO necessarily have PCOS. And not all women with PCOS necessarily have PCO. There is a subtle but important difference between the two, and it’s worth understanding the nuances of each — especially if you are planning a pregnancy. 

In this article, we’ll cover the key differences of PCO vs. PCOS, clarify some misconceptions, and shed light on what a PCO and/or PCOS diagnosis may mean for your fertility and long-term health. 

What Is PCO?

PCO, ‘polycystic ovaries’, or ‘multifollicular ovaries’ are all medical terms used to describe ovaries that have: 

• Become enlarged and 
• Contain more ovarian follicles than normal 

To recap — ovarian follicles are fluid-filled sacs inside the ovaries, with each sac containing an immature egg. Normally, follicles grow, support egg development, and eventually burst open during ovulation. In cases of PCO however, some follicles are unable to develop. This causes excess follicles to accumulate in one or both of the ovaries. 

Polycystic ovaries are considered a common variant of normal ovaries. For the most part, they are completely harmless and do not always interfere with fertility. The general consensus is that around 20-25% of women of reproductive age have PCO, with one study estimating the prevalence of PCO to be 22%.

It’s important to note that although ovarian follicles may look like tiny cysts in an ultrasound, they are not actually cysts. Unfortunately, this only contributes to the confusion surrounding polycystic ovaries and polycystic ovary syndrome. 

Symptoms

Typically, individuals with PCO do not have any noticeable symptoms. If symptoms do occur, they may include: 

• Irregular periods
• Irregular ovulation
• Mild pelvic pain 

In the vast majority of cases, PCO is not discovered until an ultrasound – either for pregnancy or for another condition. 

Diagnosis

Multifollicular ovaries are diagnosed via ultrasound. Current guidance states that a PCO diagnosis should be given if there are more than 10 follicles in at least one ovary. These follicles can be up to 8mm each in size. When viewed on an ultrasound scan, the excess follicles may appear slightly enlarged. 

What Is PCOS?

Unlike polycystic ovaries (PCO) which are a physical characteristic of the ovaries, polycystic ovary syndrome (PCOS) is a metabolic condition. This means it interferes with hormone levels, with the key indicators being: 

• High androgen levels
• High estrogen levels
• High luteinizing hormone (LH) levels
• Insulin resistance

Here’s where it gets confusing. In some cases of PCOS, the ovaries may also become polycystic. This means an individual can have both PCOS and PCO. However, having PCO alone is not enough to diagnose PCOS. It’s also possible to have PCO but not have the hormonal characteristics of PCOS. 

PCOS is less common than PCO. However, it still affects an estimated 7-10% of women of reproductive age. 

Symptoms

Unlike PCO, most individuals with PCOS will experience some symptoms that interfere with the menstrual cycle and overall health. 

The most common symptoms related to the menstrual cycle and fertility include: 

• Bloating
• Heavy menstrual flow
• Irregular periods
• Menstrual cycles shorter than 21 days or longer than 35 days
• Difficulty getting pregnant

Other symptoms include challenges related to:

• Weight: such as unexpected weight gain and difficulty losing weight
• Skin: such as increased presence of acne, dark patches, skin tags, excess facial and body hair (hirsutism), male-pattern baldness
• Sleep: such as insomnia and difficulty falling and staying asleep
• Heart health: such as high blood pressure and hypertension

Individuals with PCOS may also experience:

• Fatigue
• Headaches and
• Mood swings 

Due to the nature of the condition and its impact on weight, heart health, and fertility, PCOS also comes with a host of long-term health risks. This includes an increased risk of:

• Diabetes
• Cardiovascular disease
• Anxiety and/or depression
• Pregnancy complications

It’s important to note that these long-term health risks are only associated with PCOS and not PCO. There are no known long-term health risks of having PCO without a PCOS diagnosis. 

Diagnosis

To diagnose PCOS, an individual must meet at least two of the following three criteria: 

• Irregular periods and ovulation and/or absence of periods and ovulation. Irregular, infrequent, or prolonged menstrual cycles are the most common signs of PCOS.
• Excess androgen levels. Abnormally high male sex hormones (androgens) are responsible for symptoms like hirsutism, acne, and weight gain. 
• Polycystic ovaries (PCO). When the ovaries become enlarged and have a minimum of 10 follicles in at least one ovary. 

Your doctor may be able to diagnose PCOS on examination if you have obvious symptoms, such as irregular periods or hirsutism. Blood testing may also be necessary to test your hormone levels. Your doctor may also want to order an ultrasound to see if you have PCO. 

Again, having PCO is just one of the signs of PCOS — but it is not the only element required for a PCOS diagnosis. 

Key Differences

A PCO diagnosis is commonly mistaken for PCOS, even though they are different. The following table cuts through the noise to help you understand exactly how the two conditions differ. 

	PCO (Polycystic Ovaries)	PCOS (Polycystic Ovary Syndrome)
Definition	A common variant of the ovaries where they become enlarged and contain more ovarian follicles than normal.	A metabolic condition characterized by high androgen levels, high estrogen levels, and insulin resistance.
Prevalence	Approximately 20-25% of women of reproductive age	Approximately 7-10% of women of reproductive age
Symptoms	The majority of cases are asymptomatic. However, symptoms such as irregular menstrual cycles and mild pelvic pain may occur in some cases.	Pelvic pain, heavy menstrual flow, irregular periods, menstrual cycles shorter than 21 days or longer than 35 days, difficulty getting pregnant Unexpected weight gain, difficulty losing weight, acne, dark patches on the skin, skin tags, excess facial and body hair (hirsutism), male-pattern baldness, poor quality of sleep, high blood pressure, fatigue, headaches, and mood swings
Diagnosis	Must have more than 10 follicles in at least one ovary. Diagnosed with an ultrasound scan.	Must meet at least two of the following three criteria:  Irregular, infrequent, or prolonged menstrual cycles and irregular or absent ovulation.Excess androgen levelsPolycystic ovaries (PCO)  Diagnosed with the help of blood testing and/or an ultrasound scan.
Impact on Fertility	Little to no impact on fertility	May impact ovulation and make it more difficult to conceive.
Long-term Health Risks	Little to no known long-term health risks	Diabetes, cardiovascular disease, anxiety, depression, and pregnancy complications

How Do You Treat PCO vs. PCOS?

Treating PCO

Because PCO is a common variant of normal ovaries, it usually does not require treatment. However, if you know that you have PCO and you also experience any of the common symptoms of PCOS, make another appointment with your doctor. They can assess your symptoms and run further testing to see if you have PCOS as well.   

Treating PCOS

Treating PCOS often involves a combination of lifestyle changes and in some cases medication. Here are some of the most common treatment options a doctor may recommend following a PCOS diagnosis. 

First up is to maintain a healthy weight. Research shows that around half of PCOS patients are also overweight. The culprit behind this weight gain is insulin resistance, which can increase your blood sugar levels while also zapping your energy. Losing some weight (even just 5-10% of overall body weight) can help to improve insulin sensitivity and balance hormone levels.

Pro Tip: Avoid crash diets! Instead, embrace a balanced PCOS-friendly diet packed with lean proteins, whole grains, non-starchy vegetables, and fruits. It’s also a good idea to incorporate some form of regular exercise. Current guidance suggests a minimum of 150 minutes of moderate physical activity per week for PCOS patients. 

Next is to proactively manage your stress levels. Research shows a higher prevalence of stress among PCOS patients. Chronic stress disrupts your hormone levels. This in turn makes PCOS symptoms much worse. By keeping stress levels low, you can help promote hormone balance. 

Pro Tip: De-stressing is more than just taking a bubble bath! Think about the activities that help you rewind and pencil them in on a regular basis — whether that’s taking a walk, listening to music, journaling, reading, doing a craft, watching a film, or playing a video game. You may also benefit from taking stock of your responsibilities and/or expectations of yourself and identifying a few things to let go of. 

Last but not least, speak with your doctor about potential medications and/or supplements. For example, medications such as hormonal birth control, clomiphene citrate, metformin, and spironolactone can help improve PCOS symptoms. Supplements like inositol (vitamin B8) and vitamin D are also known to help improve insulin sensitivity and balance hormones. Before starting any medications or supplements, always speak with your doctor. They can advise on suitable treatments based on your medical history and fertility goals. 

Pro Tip: Get the perfect combination of vitamin D and inositol with Mira’s own PCOS Supplements! 

Fertility with PCO vs. PCOS

When it comes to fertility, the two key facts about PCO and PCOS you need to know are:

• With PCO, it’s still possible to conceive easily. 
• With PCOS, it’s still possible to conceive. However, it may be more difficult to conceive and fertility treatment may be necessary. 

With PCO alone, the presence of multiple follicles on the ovaries does not typically interfere with cycle regularity or ovulation. 

However, with PCOS, elevated androgen and estrogen levels can prevent ovulation from occurring regularly or even at all. This makes it difficult to conceive naturally. Weight gain due to insulin resistance also decreases the chances of natural conception.

The good news is that getting pregnant with PCOS is less a question of whether fertility treatment will work, and more a question of which fertility treatment will work. 

The first line of treatment for PCOS patients who are actively trying to conceive (TTC) is a course of clomiphene citrate (also known by the brand name Clomid). Clomiphene citrate helps to promote cycle regularity and ovulation. 

As a general reference point, women under the age of 35 have a 25% chance of getting pregnant each cycle. PCOS patients under the age of 35 who are being treated with Clomid have a 15% chance of pregnancy each cycle. Among those who are able to ovulate on Clomid, approximately 50% will become pregnant.

If pregnancy has not occurred after several cycles of treatment with Clomid, an individual is considered Clomid-resistant. In this case, a doctor may recommend in-vitro fertilization (IVF) to support conception. 

Tracking Ovulation With PCO vs. PCOS

Having PCO alone does not necessarily interfere with ovulation — meaning you’re more likely to ovulate regularly. This makes planning a pregnancy relatively straightforward, as you can start with the basic pregnancy planning methods and tools. This includes:

• Calendar-based ovulation tracking (see Mira’s own ovulation calendar)
• Cervical mucus tracking 
• Basal body temperature (BBT) tracking with a BBT thermometer
• Ovulation predictor kits (OPKs)

With PCOS, however, tracking ovulation can be a bit more difficult. This is because individuals with PCOS are more likely to have irregular periods and irregular ovulation. And if it’s more difficult to predict ovulation, it’s more difficult to predict the optimum times to plan a pregnancy. 

How Mira Can Help You Get Pregnant With PCOS

With PCOS, the more you know about how your hormones fluctuate, the easier it is to plan a pregnancy. This is where Mira comes in. 

When you use the Mira Hormone Monitor and App, you can test and track key fertility hormone concentrations in urine, including: 

• Luteinizing hormone (LH)
• Estrone-3-glucuronide (E3G)
• Pregnanediol glucuronide (PdG)
• Follicle-stimulating hormone (FSH)

When tested regularly, you can see how your hormone levels fluctuate over time; enabling you to see whether or not you’re ovulating. If you are ovulating, you’ll be able to pinpoint ovulation and see when you’re at your most fertile. 

Why OPKs Do Not Work for PCOS

Oftentimes, those who are TTC first turn to drugstore ovulation predictor kits (OPKs) to help them predict ovulation. OPKs are designed to detect the surge in LH that occurs just before ovulation. Once the LH surge is detected, sex or insemination should be planned within the next 36 hours. 

OPKs work by comparing your LH levels to an LH level threshold. If your LH levels are above the threshold, this indicates you are about to ovulate. If they are below the threshold, this means you are not about to ovulate. 

Individuals with PCOS naturally have higher than average baseline LH levels. This means they may receive positive results from drugstore OPKs — even if they are not actually about to ovulate. This can make it very confusing (and frustrating!) when planning a pregnancy with PCOS, as you may think you’re ovulating even though you’re not. 

With Mira, there is no confusion. You can chart your exact hormone concentration levels over time. This allows you to differentiate smaller LH peaks from your actual LH surge, allowing you to more accurately predict ovulation. 

To learn more about using Mira with PCOS, visit: How does Mira work with PCOS? 

Final Thoughts

At Mira, we want you to feel empowered to learn more about your body and hormones! If you found this article helpful, you may also find the following resources on our website helpful as well: 

• Webinars and Events
• E-books and Guides
• Sex Hormone Awareness Week Campaign

If you are personally struggling to navigate a recent PCO or PCOS diagnosis, we would love to support you in our Hormone Health Clinic! Our experienced hormone health practitioners can review your hormone charts, provide lifestyle guidance, and explore practical pathways to pregnancy.