Female infertility is a medical condition affecting millions of women worldwide, making it difficult or impossible to achieve pregnancy after trying for a certain period. Understanding its causes, recognizing its signs, and knowing what treatment options exist can help those facing this challenging journey navigate their path toward building a family.

How Common Is Female Infertility?

Female infertility is far more common than many people realize. At least 10% of women experience some form of infertility during their reproductive years^[1]. When looking at couples trying to conceive, approximately one in six people of reproductive age worldwide experience infertility in their lifetime^[6]. This means that if you or someone you know is struggling to get pregnant, you are far from alone.

In the United States specifically, research shows that about 19% of married women aged 15 to 49 who have never had children are unable to get pregnant after one year of trying^[17]. When we look at the bigger picture of infertility in couples, about one-third of cases are due to female factors, one-third involve both male and female factors, and the remaining cases involve male factors or remain unexplained^[2][6].

Infertility affects people across all demographics, backgrounds, and walks of life. The chances of experiencing infertility increase significantly with age, particularly for women in their mid-30s and beyond. Understanding that this is a widespread medical condition can help reduce feelings of isolation and shame that many women experience when facing fertility challenges.

What Causes Female Infertility?

Female infertility can result from many different factors, and in some cases, multiple factors may be present at the same time. Understanding what causes infertility is an important first step in finding the right treatment approach.

Ovulation problems are the most common cause of female infertility, accounting for approximately 25% of all cases^[3]. Ovulation is the process where an egg is released from one of the ovaries each month. When this process doesn’t happen regularly or at all, pregnancy becomes very difficult or impossible. The brain’s hypothalamus (a small region that controls many body functions) and the pituitary gland (which makes important hormones) must work together properly to trigger the ovaries to release eggs. If this delicate system is disrupted, ovulation may not occur^[8].

Conditions like polycystic ovary syndrome, commonly called PCOS, are a leading cause of ovulation problems. About 70% of women with ovulation disorders have PCOS^[14]. This condition affects how the ovaries work and can prevent eggs from being released regularly. Other hormonal imbalances involving the thyroid gland, prolactin levels, or problems with the pituitary gland can also disrupt ovulation^[1][9].

Problems with the fallopian tubes represent another significant cause of infertility. These are the tubes that connect the ovaries to the uterus, and eggs must travel through them to reach the uterus. If the tubes are blocked, scarred, or damaged, the egg cannot make this journey. Pelvic inflammatory disease, or PID, is the most common cause of tubal problems^[1]. PID often results from untreated sexually transmitted infections, particularly chlamydia and gonorrhea^[1][6]. Tubal blockage accounts for about 11% of female infertility cases, while other tubal or uterine abnormalities account for another 11%^[3].

Endometriosis is a condition where tissue similar to the lining inside the uterus grows outside of it, often on the ovaries, fallopian tubes, or other pelvic structures. This condition causes about 15% of female infertility cases^[3]. Endometriosis can cause scarring of the fallopian tubes and may interfere with how eggs are released and fertilized^[1].

Uterine problems, including polyps (small growths), fibroids (non-cancerous growths in the uterine wall), or adhesions (scar tissue inside the uterus), can all affect fertility. These issues may prevent a fertilized egg from attaching properly to the uterine wall, which is necessary for pregnancy to begin^[1][8].

Age-related decline in egg quality and quantity is a natural biological reality that significantly impacts fertility. Women are born with all the eggs they will ever have, and this supply naturally decreases over time. Additionally, as eggs age, they are more likely to have chromosomal abnormalities, which can prevent fertilization or lead to miscarriage^[1][8]. By age 40, a woman’s chance of pregnancy per menstrual cycle drops to only about 5%^[8].

Sometimes, despite thorough testing, doctors cannot find a specific cause for infertility. This is called unexplained infertility, and it affects about one in ten couples investigated for fertility problems^[8]. Even though no clear cause can be identified, many of these couples can still achieve pregnancy with appropriate treatment.

Risk Factors That Increase the Chance of Infertility

Certain factors can increase a woman’s risk of experiencing infertility. Being aware of these risk factors can help women make informed decisions about their reproductive health and seek help earlier if needed.

Age is the single most important risk factor for female infertility. Fertility naturally begins to decline in a woman’s early 30s, with a more rapid decline after age 35^[7]. Women who are 35 or older are generally advised to seek fertility evaluation after just six months of trying to conceive, rather than waiting a full year, because time becomes increasingly critical^[1][2].

Lifestyle factors play a significant role in fertility. Smoking not only reduces the chances of pregnancy but also increases the risk of miscarriage and causes women to go through menopause about two years earlier than non-smokers^[9][20]. Weight is another important factor—both being significantly overweight and being underweight can affect fertility^[7][19][20]. Maintaining a healthy body weight through balanced nutrition and regular exercise supports reproductive health.

A history of sexually transmitted infections puts women at higher risk for infertility, particularly if these infections were not treated promptly. Untreated chlamydia and gonorrhea can lead to pelvic inflammatory disease, which damages the fallopian tubes and significantly reduces fertility^[1][7]. This is why preventing STIs through safe sex practices and getting prompt treatment if an infection occurs is so important for protecting future fertility.

Previous pelvic or abdominal surgery can create scar tissue that interferes with fertility. Surgeries involving the reproductive organs, such as procedures for removing ovarian cysts, treating endometriosis, or addressing uterine problems, may sometimes lead to scarring that affects fertility^[9]. Women who have undergone such procedures should discuss potential fertility implications with their healthcare provider.

Extreme exercise, such as consistently running more than 6 to 10 miles per day, can strain the body and affect reproductive function^[20]. While regular physical activity is healthy and supports fertility, excessive exercise can disrupt the hormonal balance needed for regular ovulation. Similarly, high levels of stress may impact fertility, though the exact mechanisms are still being studied^[7].

Certain medical treatments, including some medications and cancer treatments like chemotherapy, can affect fertility. Chemotherapy can sometimes cause ovarian failure, meaning the ovaries stop working properly^[9]. Women facing treatments that might affect their fertility should discuss fertility preservation options with their medical team before starting treatment.

Family history can also provide important clues about fertility risk. For example, if a woman’s mother experienced early menopause or struggled with fertility, she may face similar challenges^[7]. Discussing family reproductive history with a healthcare provider can help identify potential risks early.

Signs and Symptoms of Female Infertility

The primary sign of infertility is the inability to become pregnant after trying for an appropriate length of time. For women under 35, this means trying unsuccessfully for 12 months. For women 35 and older, the timeframe is six months^[1][2]. Trying to conceive means having regular, unprotected sexual intercourse without achieving pregnancy.

Irregular or absent menstrual periods can be an important warning sign of potential fertility problems. A normal menstrual cycle typically occurs every 21 to 35 days. Periods that are consistently shorter than 21 days, longer than 35 days, or that vary greatly from month to month may indicate that ovulation is not occurring regularly^[2][17]. Complete absence of menstruation, except during pregnancy or breastfeeding, also suggests ovulation problems.

Some women with fertility problems may experience other symptoms related to underlying conditions. For example, women with PCOS might notice excess facial or body hair, acne, or weight gain. Women with endometriosis often experience very painful periods, pain during intercourse, or chronic pelvic pain. However, it’s important to note that many women with infertility have no obvious symptoms other than the inability to conceive^[1].

Recurrent pregnancy loss—having two or more miscarriages—is also considered a form of infertility. This pattern indicates that while conception may be occurring, something is preventing the pregnancy from continuing normally^[4]. Women experiencing repeated miscarriages should seek specialized evaluation.

How to Prevent or Reduce the Risk of Infertility

While not all causes of infertility can be prevented, there are several steps women can take to protect their reproductive health and maintain optimal fertility for as long as possible.

Maintaining a healthy body weight is one of the most important modifiable factors. Being significantly overweight or underweight can disrupt the hormonal signals needed for regular ovulation^[19][20]. Working toward a weight that is healthy for your body through balanced nutrition and regular physical activity supports reproductive function. However, it’s important to avoid excessive exercise, which can have the opposite effect.

Protecting yourself from sexually transmitted infections is crucial for preserving fertility. Always use protection during sexual activity if you’re not in a mutually monogamous relationship with a partner who has tested negative for STIs. If you think you may have been exposed to an STI, seek testing and treatment promptly^[20]. Early treatment can prevent infections from progressing to pelvic inflammatory disease and causing permanent damage to the fallopian tubes.

Not smoking—or quitting if you currently smoke—is essential for protecting fertility and overall health. Smoking accelerates the loss of eggs and can damage the reproductive system in multiple ways^[9][19][20]. The same applies to illegal drug use, which can significantly impair fertility.

Limiting caffeine and alcohol intake supports reproductive health. While moderate consumption may be acceptable, excessive amounts of either substance can negatively affect fertility^[19]. Discussing appropriate limits with your healthcare provider can help you make informed choices.

Managing stress through healthy coping strategies, adequate sleep, and self-care activities may benefit fertility. While stress alone rarely causes infertility, reducing stress levels supports overall health and well-being during the challenging process of trying to conceive^[20].

Being aware of your own fertility timeline is important, especially as you get older. If you know you want to have children but aren’t ready yet, consider having a conversation with your healthcare provider about your fertility status and options. For women facing medical treatments that might affect fertility, such as cancer treatment, discussing fertility preservation options beforehand can protect future reproductive potential^[20].

Regular health check-ups that include screening for conditions affecting fertility, such as thyroid disorders or diabetes, help identify and treat problems early. Well-controlled chronic conditions are less likely to interfere with fertility than poorly managed ones^[19].

How the Body Changes with Female Infertility

Understanding what happens in the body when infertility occurs helps explain why pregnancy becomes difficult or impossible. Normal fertility requires a complex series of events to occur precisely and in the right sequence each month.

In a normally functioning reproductive system, the hypothalamus in the brain releases hormones that signal the pituitary gland, which then releases hormones that travel to the ovaries. These hormones tell the ovaries to ripen one or more eggs each month. Around day 14 of a typical 28-day cycle, ovulation occurs—one mature egg is released from the ovary and swept into the nearby fallopian tube^[8].

If sperm are present, fertilization normally occurs in the fallopian tube. The fertilized egg then travels down the tube toward the uterus, a journey that takes several days. By the time it reaches the uterus, it has developed into an early embryo. The embryo must then successfully implant into the thickened uterine lining, which has been prepared by hormones to receive it. Once implantation occurs, pregnancy begins^[8].

When ovulation problems exist, the hormonal signals that should trigger egg release don’t work properly. The hypothalamus or pituitary gland may not produce the right hormones in the right amounts, or the ovaries may not respond appropriately to these signals. In conditions like PCOS, multiple small follicles (fluid-filled sacs that normally contain eggs) may develop on the ovaries, but these follicles don’t mature properly and don’t release eggs regularly^[8][9].

In cases of tubal damage, the pathway for the egg to travel from the ovary to the uterus is compromised. Scarring from infections or endometriosis can block the tubes completely, making it impossible for sperm to reach the egg or for a fertilized egg to reach the uterus. Partial blockages or damage to the delicate hair-like structures inside the tubes that help move the egg along can also prevent normal function^[6].

Uterine problems affect the environment where an embryo must implant and develop. Fibroids may distort the uterine cavity or interfere with blood flow. Polyps can occupy space where an embryo would normally implant. Adhesions or scar tissue can prevent the uterine lining from developing properly each month or can physically prevent an embryo from implanting^[1].

With endometriosis, tissue similar to the uterine lining grows in places it shouldn’t be. Each month when hormones cause the uterine lining to thicken and then shed during menstruation, these misplaced tissues also respond to the same hormones. However, because they’re outside the uterus, they have no way to leave the body. This causes inflammation, pain, and the formation of scar tissue. The scarring can damage the ovaries and fallopian tubes, interfere with ovulation, and create an inflammatory environment that makes pregnancy less likely^[8][9].

Age-related changes in fertility involve both the quantity and quality of eggs. As women age, the number of eggs in the ovaries steadily decreases. Additionally, the eggs that remain are more likely to have chromosomal abnormalities. These abnormal eggs may not fertilize properly, or if they do fertilize, the resulting embryo may not be viable, leading to failed implantation or early miscarriage^[1][8].

Hormonal imbalances from thyroid problems, elevated prolactin, or other endocrine disorders disrupt the carefully orchestrated hormone signals needed for ovulation and maintaining early pregnancy. For example, an underactive or overactive thyroid can prevent regular ovulation. High prolactin levels can interfere with the hormones needed to trigger egg release^[1][9].

Understanding these underlying mechanisms helps explain why different types of infertility require different treatment approaches. Treatments aim to correct or bypass the specific problem preventing pregnancy, whether that’s stimulating ovulation, repairing damaged tubes, removing uterine growths, or using assisted reproductive technologies to accomplish outside the body what isn’t happening naturally.