“Even if it’s not how they had imagined or planned, the bottom line is that there are options available for people experiencing infertility who want to become parents,” says Eve C. Feinberg, MD, a reproductive endocrinologist and infertility specialist at Northwestern Medicine. “The silver lining of fertility treatment is optimizing your health from preconception to delivery.”

What Is Infertility?

Infertility is defined as not being able to get pregnant or stay pregnant after a set amount of time:

• For people younger than 35: After 12 months of regularly trying to conceive naturally, see a fertility specialist.  
• For people 35 and older: After six months of trying to conceive naturally, it’s reasonable to see a specialist to undergo testing.

Infertility may include:

• Difficulty conceiving
• Repeated pregnancy loss
• Not being able to carry a pregnancy to term

These medical definitions are used to help determine when testing or treatment may be appropriate. They are not meant to put pressure on individuals or couples.

How Common Is Infertility?

According to the World Health Organization, one in six people experiences infertility at some point in their lives. That’s about 17% of adults worldwide.

Several factors may contribute to infertility rates, including:

• More people choosing to have children later in life, when fertility naturally begins to decline
• Lifestyle factors, such as weight gain, poor sleep, high stress or lack of physical activity

Knowing how common infertility is can help reduce stigma. Many people are navigating similar challenges, even if they’re not talking about it openly.

Who Does Infertility Affect?

Anyone can experience infertility. Infertility can involve female* factors, male factors or both:

• Female infertility is the sole or contributing factor in about 50% of cases.
• Infertility in men is the sole or contributing factor in about 40% of cases.
• Both partners contribute in roughly 35% of cases.

What Causes Infertility?

There are several causes of infertility, but age is one of the strongest predictors, particularly for people with ovaries:

• Egg quantity and quality decline with age.
• The chances of getting pregnant each month decrease after 35.
• The risk of miscarriage and genetic conditions increase after 35.

Causes of infertility in women

Pregnancy requires a complex sequence of events. During the menstrual cycle, the ovaries must mature and release an egg, sperm must reach the egg, fertilization must occur and the embryo must implant in the uterus.

Disruption at any step can affect fertility.

Common causes of infertility in women include:

• Polycystic ovary syndrome (PCOS), which interferes with ovulation
• Endometriosis, which can cause inflammation and scar tissue
• Ovarian cysts or reduced egg quality
• Uterine fibroids that affect implantation
• Blocked fallopian tubes, often due to infection or prior surgery
• Pelvic inflammatory disease, which can damage reproductive organs

If the egg and sperm cannot meet, or if a fertilized egg cannot implant in the uterus, pregnancy cannot occur.

Causes of infertility in men

Male fertility depends on healthy sperm production and function. Common issues include:

• Low sperm count
• Poor sperm movement or shape
• Hormonal imbalances
• Testicular injury or prior illness
• Erectile or ejaculatory dysfunction

Male fertility problems are often highly treatable once identified.

Other causes

Some causes of infertility can run in families. Conditions like PCOS, early menopause or chromosomal disorders may have a genetic component. Genetic testing can sometimes help identify inherited risks.

Smoking, excessive alcohol use and excess weight can also play a role in infertility.

What About “Unexplained Infertility”?

“Unexplained infertility” means that standard testing has not identified a clear cause for difficulty conceiving. This diagnosis can feel frustrating, but it is fairly common, and it doesn’t mean pregnancy isn’t possible. Many people with this diagnosis can conceive with time, lifestyle changes or the help of fertility treatments.

Even when the cause isn’t clear, a fertility specialist can recommend options that may improve the odds of pregnancy based on age, health history and how long someone has been trying to conceive. The focus is on moving forward with a plan rather than finding a single answer.

When Should Someone Seek Fertility Care?

Consider seeing a fertility specialist if:

• Pregnancy has not occurred after one year of trying (or six months if you’re over age 35)
• Menstrual cycles are irregular or absent
• You have a known reproductive condition
• You have a history of repeated miscarriages
• A prior infection or surgery may have affected your reproductive organs

Early evaluation can shorten the time to diagnosis and treatment.

What To Expect at a Fertility Evaluation

A fertility evaluation may include:

• Blood tests to check hormones
• Semen analysis to review sperm health
• Imaging tests to evaluate the uterus and fallopian tubes
• Ultrasound of the ovaries
• Genetic carrier screening

At‑home tests do not reliably predict fertility on their own.

How Is Infertility Treated?

Treatment depends on the cause and may include:

• Medications used to stimulate ovulation or regulate hormones
• Surgery to correct structural issues
• Assisted reproductive technologies

Treatment plans are personalized and may evolve over time as new information becomes available.

Assisted reproductive technologies

Assisted reproductive technology (ART) refers to medical treatments that help with fertilization or early embryo development when pregnancy doesn’t happen on its own. These options are often used when timing, age or other fertility factors make conception more challenging.

ART may include:

• Intrauterine insemination (IUI): Washed sperm is placed directly into the uterus around the time of ovulation to improve the chance of fertilization.
• In vitro fertilization (IVF): Eggs are collected from the ovaries and combined with sperm in a laboratory. If fertilization is successful, one or more embryos are transferred to the uterus.
• Egg freezing: Eggs are collected and frozen for possible use in the future. This option is often used for fertility preservation when pregnancy is planned for later or before medical treatment that may affect fertility.

Advanced IVF techniques may also include:

• Genetic testing of embryos to reduce the risk of passing on certain genetic conditions or to test for chromosome abnormality (aneuploidy)
• Embryo selection to help identify embryos most likely to result in pregnancy

A fertility specialist can help determine which assisted reproductive options may be right for you based on your goals, health history and timing.

Other Paths to Parenthood

For some individuals or couples, biological pregnancy may not be possible or preferred. Third‑party reproduction options are also possible. They include:

• Using donor eggs or donor sperm
• Using a gestational carrier

These options help many people become parents when biological pregnancy is not possible.

Why Getting Help Early Matters

Infertility is often misunderstood, and some people hesitate to get help because they feel discouraged, embarrassed or unsure of next steps. But infertility is a medical condition, and effective care is available.                                                    

“If you’re having trouble conceiving, see a fertility specialist,” says Dr. Feinberg. “You don’t have to face infertility alone. We can help an overwhelming majority of people with infertility become parents.”

Reaching out early can reduce emotional stress, clarify what may be affecting fertility and open the door to more options. Even if treatment isn’t needed right away, getting answers and support can help you move forward with greater confidence and peace of mind.

*Scientists do not always collect information from participants about gender identity. To avoid misrepresenting the results of this research, we use the same terminology as the study authors.