Fertility isn’t a single switch you flip. It’s the result of dozens of biological processes working together, and most of them respond to changes you can actually make. Whether you’re preparing to start trying or have been at it for a while, the steps that improve your chances are well-supported by research and largely within your control.
How Age Affects Your Chances
Age is the single strongest predictor of natural conception, and understanding the real numbers helps you plan realistically. A large North American preconception study tracked couples actively trying to conceive and measured cumulative pregnancy rates over 12 cycles. Women aged 25 to 30 had roughly a 78 to 79% chance of conceiving within a year. That number held relatively steady through the early 30s, with women aged 31 to 33 reaching about 77%. The decline becomes more noticeable after 34, dropping to around 75% by ages 34 to 36, then 67% by ages 37 to 39, and 56% for women 40 to 45.
The important takeaway: fertility doesn’t fall off a cliff at 35. It declines gradually, with the steepest drop happening after 37. After adjusting for lifestyle factors, women aged 37 to 39 conceived at about 60% the rate of women in their early 20s, and women 40 to 45 at about 40% the rate. These are averages, not destiny, but they underscore why optimizing everything else matters more as you get older.
Track Your Fertile Window
You can only conceive during a narrow window each cycle, and timing intercourse correctly is one of the simplest ways to improve your odds. The surge in luteinizing hormone (LH) that triggers ovulation begins about 36 hours before the egg is released. The peak of that surge occurs 10 to 12 hours before ovulation. Over-the-counter ovulation predictor kits detect this LH surge in your urine, giving you a reliable heads-up.
Your most fertile days are the two to three days leading up to ovulation and the day of ovulation itself. Cervical mucus also provides a useful signal: as you approach ovulation, it becomes clear, slippery, and stretchy, resembling raw egg whites. This type of mucus helps sperm survive and travel. If you notice that change and get a positive ovulation test around the same time, you’ve identified your window.
Reach a Fertility-Friendly Weight
Body weight has a direct effect on ovulation. Women with a BMI above 27 have roughly 2.4 times the risk of anovulatory infertility (meaning their bodies stop releasing eggs regularly) compared to women in the normal BMI range of 18.5 to 24.9. That risk climbs further with higher BMI. Data from the Nurses’ Health Study shows the relationship is linear: a BMI of 28 to 30 roughly doubles the risk, and a BMI above 32 nearly triples it.
Where you carry fat matters too. Abdominal fat is more disruptive to ovulation than total body fat, likely because it produces more of the inflammatory signals that interfere with reproductive hormones. The good news is that the threshold for improvement is modest. Losing just 5 to 10% of body weight often restores regular ovulatory cycles in women who’ve stopped ovulating due to excess weight. For a 200-pound woman, that’s 10 to 20 pounds.
Being underweight also disrupts ovulation. Very low body fat can shut down reproductive hormone production entirely. If your periods have become irregular or stopped and your BMI is below 18.5, gaining weight is likely the most effective fertility intervention available to you.
Eat for Reproductive Health
The Mediterranean dietary pattern, built around vegetables, fruits, whole grains, legumes, olive oil, fish, and limited red meat, has the strongest fertility evidence of any eating style. Multiple studies of women undergoing fertility treatment found that higher adherence to this pattern nearly doubled clinical pregnancy rates and increased live birth rates by roughly 2.6 times compared to low adherence. Even among women conceiving naturally, better overall diet quality before conception was associated with a 65% increase in the likelihood of a successful ongoing pregnancy.
Women who scored low on Mediterranean diet adherence were also more likely to have an unexpectedly poor response to fertility treatment, producing fewer eggs than expected. The pattern’s benefits likely come from its combination of antioxidants, healthy fats, and anti-inflammatory compounds, all of which support egg quality and hormone balance. You don’t need to follow a rigid meal plan. Shifting toward more plant foods, using olive oil as your primary fat, eating fish a couple of times a week, and cutting back on processed food captures most of the benefit.
Supplements That Support Egg Quality
Folic acid is non-negotiable if you’re trying to conceive. It prevents neural tube defects in early pregnancy, and since these defects form before most women know they’re pregnant, you should be taking at least 400 micrograms daily well before conception.
CoQ10 is an antioxidant that supports the energy production inside your egg cells, which becomes increasingly important with age. For women with normal ovarian reserve, 200 mg daily for at least 30 days before trying to conceive is a reasonable starting point. Women with diminished ovarian reserve may benefit from a higher dose of 600 mg daily for 60 days. CoQ10 has a wide safety margin, with research showing daily doses up to 1,200 mg are well tolerated.
Vitamin D deficiency is common and has been linked to reduced fertility in observational studies. Getting your levels checked and supplementing if you’re low is a straightforward step worth taking.
Male Fertility Matters Just as Much
About half of all fertility problems involve a male factor, so optimizing sperm health is equally important. Sperm take roughly 74 days to develop fully, which means lifestyle changes need about two to three months to show results in semen quality.
Weight loss in men produces measurable improvements. A 14-week weight loss program reduced DNA damage in sperm and increased total motile sperm count. Sperm shape (morphology) also improved significantly. Smoking is another major factor. Heavy smokers have notably worse semen quality compared to lighter smokers, and even reducing the number of daily cigarettes, not just quitting entirely, improves sperm parameters.
Heat is the often-overlooked variable. Testicles sit outside the body because sperm production requires a temperature slightly below core body temperature. Prolonged laptop use on the lap, frequent hot tub sessions, tight underwear, and extended cycling can all raise scrotal temperature enough to impair sperm production. Switching to boxers, taking breaks from seated positions, and avoiding excessive heat exposure are simple fixes.
Reduce Stress, Protect Your Hormones
Chronic stress doesn’t just feel bad. It directly suppresses the hormonal cascade that triggers ovulation. When your body produces high levels of the stress hormone cortisol, it inhibits the brain signals that tell your ovaries to mature and release an egg. Specifically, cortisol suppresses the release of the master reproductive hormone GnRH, reduces LH output from the pituitary gland, and even interferes with hormone function at the level of the ovaries and testes themselves. This effect operates at every level of the reproductive hormone chain.
The practical implication is that stress management isn’t a soft recommendation. Regular exercise (moderate, not extreme), adequate sleep, and whatever genuinely helps you decompress, whether that’s meditation, time outdoors, or therapy, can have real physiological effects on your fertility hormones.
Avoid Hormone-Disrupting Chemicals
Endocrine-disrupting chemicals are synthetic compounds that mimic or block your natural hormones. They’re found in plastic food containers, personal care products, cosmetics, pesticides, and nonstick cookware. BPA and phthalates are the most studied, and both have been shown to interfere with reproductive function. BPA mimics estrogen and binds to estrogen receptors, disrupting follicle development and reducing egg quality. It can also alter DNA methylation patterns in ways that impair long-term fertility. Phthalates, common in fragranced products and flexible plastics, interfere with the timing of LH release and can disrupt ovulation.
Practical steps to reduce your exposure: store food in glass or stainless steel instead of plastic, avoid heating food in plastic containers, choose fragrance-free personal care products, eat organic produce when possible (especially for high-pesticide crops), and filter your drinking water. You can’t eliminate exposure entirely, but reducing it meaningfully is straightforward.
PCOS and Restoring Ovulation
Polycystic ovary syndrome is one of the most common causes of irregular or absent ovulation, and it’s also one of the most treatable. If you have PCOS and carry excess weight, a 5 to 10% weight loss often restores ovulatory cycles on its own, without medication. This should be the first approach tried.
When lifestyle changes aren’t enough, several medications can induce ovulation. Letrozole (an aromatase inhibitor) has become the preferred first-line treatment in many clinics. Clomiphene citrate, a longer-established option, stimulates the brain to produce more of the hormones that trigger egg development. For women with insulin resistance, which is common in PCOS, metformin can improve hormonal balance and support ovulation either alone or alongside other treatments. Your doctor will typically start with the lowest effective dose and adjust over a few cycles based on your response.
When to Get Evaluated
The American Society for Reproductive Medicine recommends starting a fertility evaluation after 12 months of trying if you’re under 35, and after 6 months if you’re 35 or older. For women over 40, earlier evaluation is appropriate. Certain conditions warrant immediate evaluation regardless of how long you’ve been trying: irregular or absent periods, cycles shorter than 25 days, known or suspected endometriosis, a history of chemotherapy or radiation, or any known male fertility concerns. If any of these apply, there’s no reason to wait out a standard timeline before seeking help.