Subfertility: You're Not Infertile, But You're Not Getting Pregnant — Here's What That Means

You've been trying to conceive for a while. You know you're ovulating (at least sometimes), and menstruating (even if irregularly), and your partner is producing sperm. And yet, you're not getting pregnant.

This can be frustrating, discouraging, and confusing. But it's a familiar experience for many who want (and try) to become parents. So, what gives?

If you're not technically infertile, you could be facing subfertility. What does this mean, exactly? Here's what to know about subfertility, including the possible causes, what the chances are of still getting pregnant, and how it's different from infertility.

Subfertility definition: the fertility gray area no one talks about

Subfertility means fertility is reduced but not totally absent, so conceiving naturally without medical support is still possible. It's usually defined as not getting pregnant despite trying to conceive for several cycles with unprotected sex.

The timeline

Those trying to conceive without success for at least six months (menstrual cycles) — but aren't at the 12-month mark — are generally considered subfertile. The infertility threshold is met once you've been trying for at least a year with regular, unprotected sex.

The key differentiator

Clinically speaking, pregnancy can still happen naturally with subfertility, but may just be taking longer than average. This distinction matters in terms of how you feel emotionally and how you choose to move forward.

Like flipping a coin, you're not more or less likely to become pregnant after a certain number of failed cycles. It's possible the metaphorical coin just happened to land on tails the last six or more times.

Though there are possible causes of subfertility (which we'll cover below), it can feel like the "luck of the draw" if you're otherwise not facing any known fertility issues.

Infertility vs. subfertility: more than just semantics

Some healthcare providers might use the terms interchangeably. This can be confusing for a patient hoping to get pregnant because they're really not the same thing.

• Infertility: The inability to conceive after at least 12 months of trying through unprotected sex (or at least six months for those over 35).

• Subfertility: Reduced fertility or delayed conception, with the possibility of natural pregnancy still intact.

The likelihood factor

Infertility means natural conception is unlikely (though it's often hard to predict whether it's an absolute impossibility). Meanwhile, subfertility means conceiving through unprotected sex is delayed but still possible.

Getting a diagnosis for subfertility versus infertility might affect insurance coverage and treatment urgency, not to mention how you process the experience emotionally.

Some sources define subfertility as not conceiving after a year of trying naturally, rather than six months. This can make things more confusing for patients while affecting how and when it's diagnosed.

The truth

The causes of subfertility and infertility are often the same. It's just the timeline that differs.

According to a 2003 analysis of several studies published in the peer-reviewed journal BMJ, one in six couples who try to get pregnant experience delayed conception. And about half of those couples will go on to conceive naturally without fertility treatment. The other half aren't necessarily infertile but might need medical intervention to get pregnant.

What being subfertile actually feels like (the part medical definitions miss)

The limbo of being not quite infertile but definitely not pregnant can be not only deeply frustrating but also make it hard to know what your next move is.

Many couples fall into decision paralysis: Do we keep trying naturally or seek help now?

Then there's the financial component: Is it worth paying for fertility testing or exploring other routes when we still might get pregnant the old-fashioned way?

For anyone actively trying to get pregnant, the monthly loop of hope, disappointment, and back to square one can be discouraging. Meanwhile, seeing friends conceive easily while you're stuck in month seven, eight, or nine can slowly erode your patience and feel isolating.

Well-meaning people might ask, "Why not just relax instead of worrying about it?" (helpful, thanks!) or "Have you tried…?" Knowing how to politely respond while maintaining your sanity can add to your growing pile of concerns.

Jessica Bell van der Wal, Co-Founder & CEO of Frame Fertility, knows this firsthand. A lot of her own fertility issues stemmed from chronic conditions that had gone undiagnosed for years. Her message to anyone stuck in that gray area: "It's not your fault. You did nothing wrong. You didn't miss something. You didn't forget to do anything. The system just isn't set up to guide you in the way you need and deserve."

What causes subfertility (and why it matters for what you do next)

While they may not end in the same outcomes, subfertility and infertility have the same root causes. The difference here is the severity or whether there are multiple factors at play.

Female factors

Female factors associated with subfertility:

• Ovulation irregularities: In a Rescripted survey, a third of respondents reported going three or more months without a period — a pattern that often signals anovulation, one of the most common and underdiagnosed drivers of subfertility. Irregular cycles could also be attributed to PMOS, or polyendocrine metabolic syndrome (formerly known as PCOS), thyroid disorders, or diminished ovarian reserve. 

• Structural issues: For example, uterine abnormalities, mild endometriosis, fibroids, or polyps.

• Tubal factors: Some experience fallopian tube dysfunction with partial blockage or damage affecting fertility.

• Hormonal imbalances: This can affect cycle regularity and ovulation.

• Age-related egg quality decline: This can start in your mid-30s and accelerate after age 37.

• Lifestyle factors: Things like weight, chronic stress, smoking, and excessive exercise.

Male factors

Male factors linked to subfertility:

• Sperm count, motility, or morphology issues (which can have various causes)

• Lifestyle factors, like smoking, excessive alcohol, or heat exposure

• Varicocele (enlarged veins in the scrotum)

• Hormonal imbalances

• Medication side effects

Like women, men can face age-related fertility issues, such as reduced sperm count and quality.

Unexplained subfertility

When all the tests come back "normal" but pregnancy isn't happening, your medical team might call it unexplained subfertility.

But just because there's currently no explanation doesn't mean it's "in your head." There could be hidden factors that haven't been identified, like egg quality issues, fertilization problems, or something affecting implantation.

Still, getting this news can be frustrating, with no clear answers or treatment path.

The American Society for Reproductive Medicine (ASRM) reviewed research, systematic reviews, and observational studies from 1968 through 2019. It found that up to 30% of couples experiencing infertility are diagnosed with unexplained infertility.

Types of subfertility and understanding your specific situation

Knowing the different types of subfertility can help you make sense of your unique situation.

These are the four categories:

• Primary subfertility: Difficulty conceiving your first child.

• Secondary subfertility: Difficulty conceiving after already having a child (yes, this is incredibly common and valid).

• Age-related subfertility: When age is the main factor.

• Condition-specific subfertility: When it's tied to a health condition like PCOS or endometriosis.

When to seek help (the question everyone asks)

There's no one-size-fits-all "right" time to seek fertility help. That said, some general guidelines recommend seeing a specialist after 12 months of actively trying if you're under 35 or after six months if you're 35 or older.

Age is often one of the main factors when deciding. Trying "just a few more months" can have different implications when you're 32 than at age 38.

Also, seeking help really just means getting tested first, not necessarily treatment. Having information about your fertility can give you peace of mind or inform your next steps.

If you have irregular periods, a known medical condition, prior pelvic infections — or if your partner has been diagnosed with a health condition — you might consider being seen sooner rather than later.

Treatment options for subfertility, starting with the least invasive

Your provider might recommend lifestyle changes first, like taking supplements, exercising, quitting smoking, or working toward a healthy bodyweight. They may also suggest ovulation tracking or offer tips for timing intercourse. 

The next level of treatment is usually medication to support ovulation, such as clomiphene citrate (Clomid) or letrozole (Femara).

For couples still struggling to get pregnant, IUI (intrauterine insemination) or IVF (in vitro fertilization) might be discussed.

Even with these interventions on the table, trying naturally for a bit longer is still a valid choice for some.

The odds no one wants to talk about (but you deserve to know)

Let's lay out the stats on subfertility:

• A 2005 article published in Human Reproduction found that roughly 80% of couples conceive within the first six months of trying with well-timed intercourse.

• Of the remaining 20%, about half will conceive in the next six months without medical intervention.

• After a year, 55% of couples who don't get fertility treatment will conceive within the next three years.

• After trying for four years, around 5% are considered infertile with near-zero odds of having a spontaneous pregnancy.

Know that there's always variance with statistics, so you can't necessarily expect your personal experiences to fall within a specific timeframe.

Moving forward from the middle ground

Remember, subfertility is fairly common, and for many couples, it's temporary. Still, it's worth taking seriously and protecting your mental health while you navigate this gray area. If you need support from family, a therapist, trusted friends, or an online community, don't hesitate to reach out.

Wherever you are in your TTC journey, the next steps you take are totally valid. The decision to keep trying the natural way for a while longer or get tested sooner is absolutely okay.

There's no right or wrong way to move forward from subfertility. Do what feels right for your emotional health, what works for your finances, and what makes the most sense for you as a couple. Trust your gut — no one knows your situation better than you.