Understanding Unexplained Infertility

If you’ve been trying to conceive but haven’t had any luck — and your doctor can’t pinpoint an obvious cause — you may be diagnosed with unexplained infertility. 

Infertility is defined as the inability to conceive after one year of trying (or six months if you’re 35 or older). Normally, fertility tests identify issues such as ovulation problems, sperm abnormalities, or reproductive health conditions. However, in cases of unexplained infertility (also known as idiopathic infertility), all standard tests return normal results, leaving you with more questions than answers. Basically, you have no identifiable medical problems and everything is working as it should be, but no matter how hard you try, you can’t get pregnant. Unexplained infertility accounts for as many as 30% of cases where a couple struggles to conceive naturally. 

A diagnosis of unexplained infertility can be frustrating and disappointing, but it doesn’t mean pregnancy is impossible. Getting pregnant is still possible, even if you've been told you have unexplained infertility. While success rates vary, one study showed that about 21% of couples diagnosed with unexplained infertility were able to conceive naturally. Other research found that around 50% of couples with unexplained infertility will become parents within a year, with another 12% doing so in the following year. 

What causes unexplained infertility?

Although doctors may not be able to identify the exact cause, unexplained infertility doesn’t mean there isn’t an underlying issue — it’s simply unknown. Some potential contributing factors may include:

• Subtle hormonal imbalances
• Mild endometriosis
• Egg or sperm quality issues that standard tests don’t detect
• Problems with embryo implantation
• Unrecognized immune system factors
• Environmental or lifestyle influences. 

Medical research is continuously evolving, and doctors are learning more about lesser-known causes of fertility challenges.

An emerging explanation could be linked to the vaginal microbiome, which plays a crucial role in reproductive health. When the balance of bacteria in the vagina is off, it can lead to inflammation and increase the risk of infections, creating a less hospitable environment for conception. Studies have shown that imbalances in the vaginal microbiome can contribute to infertility, repeated pregnancy losses, and preterm births. Meanwhile, having a healthy microbiome dominated by protective bacteria is linked to better fertility, successful implantation, and more positive pregnancy outcomes. While there’s still much to learn about how the vaginal microbiome affects fertility, testing it might be a helpful new tool to enhance your chances of reproductive success.

How is unexplained infertility diagnosed?

Unexplained infertility is a diagnosis of exclusion, which means all known causes must first be ruled out. Fertility testing typically includes:

For women:

• Blood tests to check hormone levels (FSH, LH, progesterone, thyroid function)
• Testing for sexually transmitted infections (STIs)
• Ultrasound and physical exams to evaluate the ovaries, uterus, and fallopian tubes
• Anti-Müllerian Hormone (AMH) test to assess ovarian reserve and egg quality. 

For men:

• Physical examination of the testicles and penis
• Semen analysis to check for low sperm count, motility, and morphology
• STI testing. 

If these tests come back normal (you’re ovulating regularly, there are no blockages in your ovaries, and sperm analysis was good) and you’ve been trying to conceive for the recommended time frame (12 months, or six months if you’re over 35), your doctor may diagnose you with unexplained infertility. While this can be discouraging, there are still treatment options to explore.

Treatments for unexplained infertility

Fertility treatments can help overcome unexplained infertility. The most common options include:

Assisted reproductive technology

Assisted reproductive technology (ART) treatment helps individuals or couples conceive when natural conception is difficult or unlikely. ART involves handling eggs, sperm, or embryos in a laboratory setting to increase the chances of pregnancy. Common ART procedures include: 

• In vitro fertilization (IVF): IVF is a widely used fertility treatment where eggs and sperm are combined in a lab, and resulting embryos are transferred into the uterus. IVF is often recommended for couples with unexplained infertility.
• Artificial insemination: Intrauterine insemination (IUI) involves placing sperm directly into the uterus around the time of ovulation to increase the chances of fertilization. While it can be a less invasive option than IVF, research suggests that IUI may not be as effective for unexplained infertility.
• Intracytoplasmic sperm injection (ICSI): ICSI is an advanced IVF technique where a single sperm is directly injected into an egg. It may help when standard IVF has not resulted in fertilization.
• Donor eggs or sperm: For those who struggle to conceive with their eggs or sperm, using donor eggs, sperm, or embryos can be a viable alternative. This option can be particularly helpful for same-sex couples or individuals pursuing single parenthood.

Medications

Fertility drugs like clomiphene, letrozole, or gonadotropins are sometimes used to stimulate egg production in conjunction with treatments like IUI. However, since ovulation isn’t typically an issue in unexplained infertility, their effectiveness may be limited.

Lifestyle changes 

While lifestyle changes can’t guarantee conception, they can improve overall reproductive health and create a more favorable environment for pregnancy. Since unexplained infertility has no clear cause, adopting a more holistic approach to your health may increase your chances of conceiving naturally or with fertility treatments. Here’s how: 

• Limit caffeine and alcohol intake
• Avoid smoking and recreational drugs
• Manage chronic stress 
• Treat any underlying medical conditions
• Look after your vaginal microbiome 

Making changes to your lifestyle might not solve unexplained infertility by itself, but it can definitely help improve your reproductive health, support any medical treatments, and boost your overall well-being. Many couples facing unexplained infertility end up conceiving naturally with time. By taking positive steps, you can increase your chances of success and feel better along the way. Adopting healthier lifestyle habits can improve your overall well-being, but remember that infertility is never your fault.

Moving forward with unexplained infertility

Receiving a diagnosis of unexplained infertility can be emotionally challenging. However, it’s important to remember that there are still options available. Whether through lifestyle habits, fertility treatments, or alternative paths to parenthood, many infertile couples and individuals successfully build their families despite an unclear diagnosis.

FAQ

What is the main cause of unexplained infertility?

The main cause of unexplained infertility is unknown because standard fertility tests fail to identify a specific issue. However, researchers and fertility specialists believe it may be due to subtle or undetectable factors affecting conception. Some possible underlying causes include subtle hormonal imbalances, egg or sperm quality issues, implantation challenges, or imbalances in the vaginal microbiome.

Can you get pregnant naturally with unexplained infertility?

Yes. Many couples conceive naturally over time, even without fertility treatments. Fertility isn’t as straightforward as we’re made to believe, so every person (and couple) will have a different experience with an infertility diagnosis. As disheartening as it may be to be told you have unexplained infertility, it’s not impossible to get pregnant (though it may be more challenging). 

What should I do after receiving an unexplained infertility diagnosis?

The first step is to recognize that it’s not your fault, nor is it because of something you did or didn’t do. If you don’t have one already, see a fertility specialist (or ask your healthcare provider to refer you to one). They will put together a plan of action — whether that’s ovarian stimulation, in vitro fertilization, intrauterine insemination, or more — tailored to you and your partner’s age, lifestyle, and medical history. They may also recommend lifestyle adjustments to support your overall well-being and boost your chances of conceiving. If you’re struggling with the diagnosis, consider reaching out to support groups or counseling to navigate the emotional impact of infertility. Unexplained infertility affects many couples, so you’re definitely not alone.