There is perhaps nothing more frustrating than a false positive pregnancy test. One minute you’re celebrating impending parenthood. And the next you’re grieving a baby who never was. PCOS will not cause a false positive pregnancy test. In fact, false positive pregnancy tests are so rare that most women will never have one. PCOS can, however, affect your ability to get pregnant. It also increases your risk of a very early miscarriage. Early miscarriages -- called chemical pregnancies -- are easy to confuse with false positives, since tests will initially result as positive and then later tests result as negative. Here’s what you need to know about PCOS, causes of false positive pregnancy tests, and infertility.

Pregnancy Test 101: Why False Positive Tests are Rare

To understand false negatives and false positives, you first must understand how pregnancy tests work. Pregnancy tests measure HCG levels in the blood and urine. Beginning with implantation, the body produces progressively higher levels of HCG to sustain an early pregnancy. Most pregnancy tests are sensitive enough to detect HCG levels around the time a woman misses her period, though some can detect HCG levels a little earlier. Very few substances can mimic HCG, and no medical conditions have been consistently linked to false positive pregnancy tests. Because pregnancy tests measure HCG levels, however, false negatives are very common. If you test before implantation, you will get a negative result no matter how sensitive the test is. Even a few days later, the result may still be negative if the test is not sensitive enough or HCG levels have not yet risen. For this reason, false negative tests are very common. Indeed, many pregnant women get several negative tests right before finally getting a positive. The earlier you test after ovulation, the more likely you are to get a false negative. Sometimes a person gets a positive test and then a negative. When this happens, it is still very unlikely that the positive test was false. Instead, the more likely culprits are:
  • The negative test is less sensitive than the positive test, and is not accurate; wait a few more days and you should get another positive.
  • A very early miscarriage. HCG levels can fall quickly when a miscarriage happens early. So if you lose the pregnancy within a few days, a pregnancy test will quickly give a negative result.
However, any time you get a positive test, you should assume that you are pregnant. A doctor can perform a blood test to check for sure, and doing so is a good idea if you have a history of infertility. Measuring HCG levels in the early days can even provide important clues about your fertility, especially if you have a history of early miscarriages. So if two tests give you different results, assume that the positive one is correct.

What Could Cause a False Positive Pregnancy Test?

It’s important to be clear: polycystic ovary syndrome (PCOS) will not cause a false positive pregnancy test. PCOS is a complex endocrine disorder that causes hormonal changes. These hormonal changes can cause a woman to ovulate infrequently or not at all. They can also affect her weight and overall health, leading to insulin resistance. Each of these factors independently can affect fertility. However, they will not cause a false positive test. What might cause a false positive test is any medication that causes the body to produce HCG, or that mimics the chemical composition of HCG. Some fertility medications can cause HCG levels to rise, causing a false positive result. Because women with PCOS are more likely to take these types of medications, they may also be more likely to get a false positive test. However, PCOS on its own will not cause a false positive test. A few other risk factors increase the risk of a false positive pregnancy test. They include:
  • Using an expired pregnancy test.
  • Mixing several different brands of pregnancy test in one box. This is because you may read instructions intended for a different test than the one you take. A negative result on one test may look like a positive result on another test. Or the test can vary in sensitivity.
  • Incorrectly using the test.
  • Leaving the test out for too long after taking it. Some tests develop an evaporation line after 10 or so minutes. When this line dries, it can look like a very faint positive.

PCOS, Early Miscarriage, and False Positive Tests

While PCOS will not cause a false positive pregnancy test, it can cause you to think you got a false positive. The scenario goes like this: You take a very early pregnancy test and get a faint positive. A few days later, you take another test and the result is negative. Shortly thereafter, you begin bleeding. You might assume that the first positive test was wrong. The more likely explanation is that you had a very early miscarriage. This is called a chemical pregnancy. A chemical pregnancy is no different from any other pregnancy or any other miscarriage -- except that you miscarry very early, before a heartbeat can be detected on ultrasound and before a doctor can verify the pregnancy in their office. PCOS increases the risk of miscarriage. In fact, women with PCOS may be up to three times more likely to suffer a miscarriage, including an early miscarriage. This means your odds of getting a positive pregnancy test that later shows a negative result are higher if you have PCOS. PCOS can make pregnancy testing more difficult in at least one other way: most women with PCOS have either irregular or very long cycles. So if you’re not carefully monitoring your cycle, pinpointing ovulation can be very difficult. This makes it harder to correctly time a pregnancy test. Consider the following example: Most women ovulate around the 14th day of their cycle. A woman with PCOS might ovulate much later, such as on the 30th day. If you estimate your ovulation date based on counting alone, you’ll pinpoint the wrong time, and you’ll test way too early. By the time you are able to get a positive test result, you might think you’re much further along in your pregnancy than you actually are. For example, if you get a positive test 14 days after ovulation, on the 44th day of your cycle, you might think you’re 30 days past ovulation -- making you more than six weeks pregnant. When the test later turns negative, you might think you had a false positive, not an early miscarriage. Variants of this scenario are extraordinarily common with PCOS, and highlight the need for careful testing to detect ovulation, as well as education about how PCOS can affect your cycle. Many women with PCOS find that a combination of charting basal body temperature, various fertility awareness methods, and ovulation testing allows them to correctly pinpoint ovulation, and identify whether they are ovulating at all. This can make it easier to determine when to test for pregnancy, greatly increasing the reliability of the first test you take.

How PCOS Affects Fertility

In addition to making pregnancy testing a confusing and frustrating endeavor, PCOS is a leading cause of infertility. Many women with PCOS do not realize they have the condition until they begin trying to get pregnant, because the symptoms are often subtle. But between 5-13% of women have this disorder, and between 70-80% will struggle with infertility. PCOS primarily affects fertility by affecting a woman’s ability to ovulate. Some women with PCOS do not ovulate at all, and many ovulate irregularly. Irregular ovulation makes it more difficult to time intercourse. Additionally, when a woman ovulates less frequently than usual, she has fewer chances to get pregnant each year. PCOS can also cause other fertility problems. Other prevalent issues include:
  • Treating PCOS when trying to get pregnant. Birth control pills are one of the most effective treatments for PCOS symptoms such as weight gain and excessive hair growth. So a woman trying to get pregnant may need to temporarily stop treatment.
  • An increased risk of miscarriage. Though doctors do not fully understand why, women with PCOS are more likely to have miscarriages, this may be due to poor egg quality.
  • Insulin resistance. PCOS can lead to insulin resistance. This may affect your ability to get or stay pregnant. Women with insulin resistance may also suffer from more pregnancy complications, including gestational diabetes.

IUI for PCOS and Other Options: Fertility Treatments for Women with PCOS

Although PCOS is a common fertility problem, it is also highly treatable. One of the best and most affordable options is ovulation induction. With ovulation induction, a woman takes a medication, usually Clomid, to induce her body to ovulate. Ovulation is a necessary prerequisite to pregnancy, but ovulation induction further increases your chances by allowing you to pinpoint the time of ovulation. This makes it easier to effectively time intercourse. Another highly effective option is intrauterine insemination (IUI).  With IUI, a doctor implants your partner’s sperm or donor sperm directly into the uterus. This ensures appropriate timing, and can also help if there is an issue with sperm quality, count, or motility. IUI greatly increases the chances of a successful pregnancy, and is a great option for people who would prefer a more affordable and less invasive option to in vitro fertilization (IVF). If IUI fails, your doctor may recommend IVF. During IVF, a doctor induces ovulation, then removes the eggs from your body. In a lab, the doctor fertilizes the eggs with sperm, then allows them to grow into embryos and reimplants them in your uterus. IVF is highly successful, even for people with complex fertility issues. There may be other options, depending on your symptoms. For example, some women with PCOS can lower their chances of a miscarriage by taking metformin. Losing weight, lifestyle changes, and PCOS-friendly diets may also help. Before trying any specific strategy make sure you talk to a fertility specialist about your options.

When to Seek Treatment for Infertility

People with PCOS should consider undergoing fertility screening before they begin trying for a baby. This is because your odds of infertility are high, and wasting several months or years trying without help can further diminish the odds of success. A fertility specialist can help you determine whether you are ovulating, make lifestyle recommendations, and prescribe medication that may be helpful. If you’ve already started trying and either have or think you may have PCOS it is best to seek help as soon as possible. Some scenarios and symptoms to be aware of are:
  • You think you have had a false positive pregnancy test.
  • You’ve had a miscarriage or chemical pregnancy.
  • Your periods are more than 35 days apart.
  • You never or only rarely get a positive ovulation test, or fertility charting indicates you may not be ovulating.
  • You have tried for longer than six months to get pregnant.
The Center of Reproductive Medicine specializes in treating all forms of infertility, including those caused by PCOS. We compassionately work with you to identify the specific causes of your infertility, then construct a comprehensive treatment plan informed by your values, timeline, goals, and budget. Infertility is lonely. But you don’t have to walk this path alone. We’re here for you, and we want you to know there is hope. Get started today and make an appointment with the Center of Reproductive Medicine.


No two people are the same, and no two infertility cases are alike. Your fertility status is personal and unique to you. Schedule your assessment with one of our fertility specialists.
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