Even when everything seems right, getting pregnant typically takes longer than most people expect. A healthy woman in her early to mid-20s has only a 25 to 30 percent chance of conceiving in any given month. That means even under ideal conditions, the odds are against you in any single cycle. Most couples conceive within six to twelve months of trying, so if you’re only a few months in, the timeline may be completely normal.
That said, there are real, identifiable reasons why conception can take longer for some people. Understanding them can help you figure out whether you need to adjust your approach, wait it out, or talk to a specialist.
Your Fertile Window Is Shorter Than You Think
You can only get pregnant during a narrow window each cycle. After ovulation, an egg survives for roughly 12 to 24 hours. Sperm can live inside the reproductive tract for about 3 to 5 days, which means your realistic fertile window is about five to six days: the few days before ovulation plus the day of ovulation itself. Sex outside that window, no matter how frequent, won’t result in pregnancy.
Many people mistime this window because they assume ovulation always happens on day 14 of a 28-day cycle. In reality, ovulation timing varies from person to person and even from month to month. Cycles that run shorter or longer than 28 days shift the ovulation date accordingly. Tracking your cycle with ovulation predictor kits (which detect a hormone surge 24 to 36 hours before ovulation) or monitoring changes in cervical mucus can help you pinpoint when you’re actually fertile rather than guessing.
Age Changes the Math Significantly
Fertility declines with age, and the drop is steeper than many people realize. In your early to mid-20s, you have roughly a 25 to 30 percent chance of conceiving each month. By age 40, that monthly chance falls to around 5 percent. The decline accelerates after 35, driven primarily by a decrease in egg quality and quantity.
This doesn’t mean pregnancy at 35 or older is unlikely. It means it often takes more cycles to achieve, and the window before seeking help is shorter. Current guidelines recommend starting a fertility evaluation after 12 months of regular unprotected intercourse if you’re under 35, after 6 months if you’re between 35 and 40, and immediately if you’re over 40 or have known risk factors for infertility.
It May Not Be a “You” Problem
When pregnancy doesn’t happen, the focus often falls on the person trying to carry. But in up to half of couples experiencing infertility, male factors play at least a partial role. Sperm count, motility (how well sperm swim), and morphology (their shape) all affect whether sperm can reach and fertilize an egg. Issues like varicoceles (enlarged veins in the scrotum), hormonal imbalances, or past infections can reduce sperm quality without any obvious symptoms.
A semen analysis is one of the simplest and earliest fertility tests available. If you’ve been trying for several months without success, having your partner tested early can save months of guesswork and prevent the common mistake of assuming the issue is entirely on one side.
Weight Affects Ovulation Directly
Both high and low body weight can interfere with your ability to ovulate, which is the single most important event in each cycle. Fat cells produce estrogen, and when you carry significant extra weight, those cells release enough estrogen that your body may respond as though you’re on hormonal birth control or already pregnant. The result: your ovaries stop releasing eggs, and your periods become irregular or stop altogether.
Being underweight (a BMI of 18.5 or below) creates the opposite problem. Too little body fat means your body may not produce enough estrogen to maintain regular cycles, leading to skipped ovulation and missed periods. In both cases, restoring a healthier weight often restores normal ovulatory cycles without any other intervention.
Stress Can Suppress Your Reproductive Hormones
Chronic stress raises cortisol levels, and cortisol directly interferes with the hormonal chain of command that triggers ovulation. Your brain’s signaling system tells your ovaries when to prepare and release an egg each month. Elevated cortisol can disrupt those signals, delaying or preventing ovulation entirely. The ovaries themselves also have receptors for stress hormones, meaning cortisol can act on them directly as well as through the brain.
This doesn’t mean you need to “just relax and it’ll happen,” which is unhelpful advice. It means that sustained, high-level stress (job loss, grief, overtraining, chronic sleep deprivation) can have a measurable physiological effect on your cycle. If your periods have become irregular during a particularly stressful time, that’s a real biological connection, not something you’re imagining.
Environmental Chemicals and Fertility
Certain industrial chemicals can mimic or block hormones in your body, and growing evidence links them to reduced fertility in both men and women. These chemicals, found in plastics, pesticides, flame retardants, and personal care products, interfere with estrogen, testosterone, and thyroid hormone pathways. They can also disrupt the same brain-to-ovary signaling system that stress affects.
The evidence is strongest on the male side. Exposure to chemicals commonly found in plastics (like BPA and phthalates), flame retardants, and certain pesticides is substantially associated with lower sperm quality. For women, the evidence is moderate but still concerning, with links to disrupted ovulation and reduced fertility. Couples struggling to conceive tend to have higher concentrations of these chemicals in their bodies compared to those who conceive easily. Reducing exposure by choosing fragrance-free products, avoiding heating food in plastic containers, and eating fewer heavily processed foods are practical steps, even if they won’t solve the problem on their own.
Common Medical Conditions That Delay Pregnancy
Several diagnosable conditions can prevent conception, and some have no obvious symptoms beyond difficulty getting pregnant.
- Polycystic ovary syndrome (PCOS) is one of the most common causes of irregular ovulation. It often shows up as irregular periods, acne, or excess hair growth, but some people have it with few noticeable signs.
- Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus, sometimes causing painful periods, but it can also silently affect the fallopian tubes or ovaries.
- Blocked fallopian tubes prevent the egg and sperm from meeting. Past pelvic infections, including sexually transmitted infections that may have caused no symptoms at the time, are a common cause.
- Thyroid disorders can disrupt ovulation even when they’re mild enough that you haven’t noticed other symptoms like fatigue or weight changes.
Many of these conditions are treatable once identified. A basic fertility workup, which typically includes blood tests to check hormone levels and an imaging test to evaluate the uterus and fallopian tubes, can uncover issues that aren’t visible from the outside.
What You Can Do Right Now
If you’ve been trying for fewer than six months and you’re under 35, the most productive thing you can do is confirm you’re timing intercourse correctly. Track ovulation rather than relying on calendar estimates. Have sex every one to two days during your fertile window rather than saving it up for one “perfect” day, since frequent intercourse during that window gives you the best odds.
Start taking folic acid if you haven’t already. It doesn’t improve your chances of conceiving, but it’s recommended while you’re trying because it protects against neural tube defects in very early pregnancy, often before you even know you’re pregnant. Beyond that, maintaining a healthy weight, getting enough sleep, and limiting alcohol are the lifestyle factors with the clearest impact on cycle regularity and egg or sperm quality.
If you’ve been trying for 12 months (or 6 months if you’re 35 to 40), a fertility evaluation for both partners is a reasonable next step. Many of the most common causes of delayed conception are straightforward to identify and often treatable without advanced procedures.