Several supplements have good evidence behind them for supporting fertility, though the right ones depend on whether you’re focused on egg quality, sperm health, ovulation, or preparing your body for pregnancy. The most universally recommended is folate, at a minimum of 400 micrograms daily, but other supplements target specific fertility challenges. Here’s what the research actually supports.
Start at Least Three Months Early
Timing matters more than most people realize. Sperm take about 74 days to fully develop from stem cells, so anything a man takes today won’t affect sperm quality for roughly two and a half months. Eggs go through a maturation window of similar length before ovulation. For both partners, starting supplements at least three months before trying to conceive gives those nutrients time to influence the cells that actually matter.
Folate: The One Everyone Needs
The American Society for Reproductive Medicine recommends that all women attempting to conceive take at least 400 micrograms of folate daily to reduce the risk of neural tube defects. Women of childbearing age generally need 600 micrograms per day. This is the single most widely agreed-upon preconception supplement across every major medical organization.
What’s worth knowing is the difference between folic acid and methylfolate. Folic acid is synthetic and doesn’t exist in nature. Your body has to convert it through multiple enzymatic steps before it can use it, and some people carry a common gene variant (MTHFR polymorphism) that makes this conversion sluggish. High doses of folic acid can actually accumulate in the blood in an unmetabolized form. Methylfolate, sometimes labeled as 5-MTHF or sold under brand names like Quatrefolic, is the biologically active form that skips the conversion process entirely and gets used by cells directly. Studies have found that 400 to 800 micrograms of methylfolate per day effectively lowers homocysteine levels, a marker linked to pregnancy complications, and it works even better than much higher doses of standard folic acid in some comparisons.
CoQ10 for Egg Quality
Coenzyme Q10 plays a central role in how cells produce energy. Eggs are among the most energy-demanding cells in the body, and as women age, the mitochondria inside eggs become less efficient. CoQ10 acts as both an antioxidant, protecting egg DNA from oxidative damage, and a fuel source for cellular energy production.
In clinical trials involving women with poor ovarian response, dosages ranged from 200 milligrams three times a day to 600 milligrams twice a day, typically taken for 8 to 12 weeks before fertility treatment. Animal studies show it reduces cell death in the supportive cells surrounding eggs, improving both egg quantity and quality. When combined with melatonin, CoQ10 produced better oocyte quality than melatonin alone. Ubiquinol is the pre-converted, more easily absorbed form of CoQ10 and is generally the better choice for supplementation.
Vitamin D and Pregnancy Rates
Vitamin D deficiency is remarkably common and directly linked to lower fertility. Multiple studies have found that blood levels of 30 ng/mL or higher are associated with significantly higher pregnancy rates. A meta-analysis of women undergoing fertility treatments found that those above 30 ng/mL had better live birth rates than women with lower levels.
Most prenatal vitamins contain some vitamin D, but often not enough to correct a deficiency. A simple blood test can tell you where you stand. If you’re below 30 ng/mL, supplementing with vitamin D3 can bring levels up over several weeks.
Inositol for PCOS and Ovulation
If you have polycystic ovary syndrome, inositol is one of the most studied supplements for restoring regular ovulation. The key is the ratio: a 40:1 combination of myo-inositol to D-chiro-inositol has been shown to be the most effective formulation for normalizing ovulation and other hormonal markers in women with PCOS. Shifting that ratio to include more D-chiro-inositol actually reduced the benefits, particularly for reproductive outcomes. Many PCOS-targeted supplements now use this specific 40:1 ratio, typically providing around 4,000 milligrams of myo-inositol combined with 100 milligrams of D-chiro-inositol per day.
DHEA for Diminished Ovarian Reserve
Women diagnosed with diminished ovarian reserve, meaning fewer remaining eggs than expected for their age, may benefit from DHEA supplementation under medical supervision. The standard protocol used across multiple clinical trials is 75 milligrams daily, usually split into three doses, taken for at least 60 days before fertility treatment.
The results from several studies are notable. In one trial, women who supplemented with DHEA for at least two months before treatment had significantly higher follicle counts and a pregnancy rate of nearly 30%, compared to about 9% in the control group. Another study in poor responders found pregnancy rates jumped from 10.5% to 47.4% per patient after DHEA supplementation. Research also shows that AMH levels, a key marker of ovarian reserve, increase in proportion to how long DHEA is taken, and that improvement in AMH is highly predictive of pregnancy success. The effect tends to be more pronounced in younger women with premature ovarian aging than in older women. DHEA is a hormone, not a simple vitamin, so this is one to discuss with a fertility specialist rather than starting on your own.
Omega-3 Fatty Acids
The omega-3 fats EPA and DHA, found in fish oil, support several aspects of reproductive function. They help maintain cell membrane stability, regulate gene expression, and influence prostaglandin production in the uterine lining. Research in multiple species shows that omega-3 supplementation alters the balance of prostaglandins in the endometrium, which may create a more favorable environment for implantation. Omega-3s also support follicular growth, the function of the corpus luteum (the structure that produces progesterone after ovulation), and hormone production. A standard dose is 1,000 to 2,000 milligrams of combined EPA and DHA daily.
Supplements for Male Fertility
Roughly half of fertility challenges involve a male factor, yet male partners are often overlooked when it comes to supplementation. L-carnitine has some of the strongest evidence for improving sperm quality. In men with low motility, supplementation at 2,000 milligrams per day for three months produced dramatic improvements in one clinical case: progressive motility went from 15% to 50%, and sperm count nearly doubled from 25 million to 49 million per milliliter. Broader research confirms that carnitine significantly improves sperm motility and shape, though its effect on overall sperm count is less consistent.
Zinc and selenium are also commonly recommended for male fertility. Both are essential for normal sperm development and act as antioxidants that protect sperm DNA from damage. CoQ10, discussed above for egg quality, similarly benefits sperm by supporting the mitochondria that power sperm movement.
What to Avoid: Vitamin A Risks
Not all supplements are safe at high doses during the preconception period. Preformed vitamin A (retinol) is the most important one to watch. Intake above 10,000 IU per day is considered a risk factor for birth defects, particularly affecting the heart, central nervous system, and urinary tract. The risk is highest during the first 60 days after conception, which is often before many women know they’re pregnant.
UK guidelines recommend avoiding supplements with more than 5,000 IU of preformed vitamin A during the prenatal period. Liver is also worth limiting because of its extremely high retinol content. The good news is that beta-carotene, the plant-based form of vitamin A found in most prenatal vitamins and in foods like sweet potatoes and carrots, has not been associated with birth defects even at high intakes. If you’re checking supplement labels, look for beta-carotene rather than retinol or retinyl palmitate as the vitamin A source. And isotretinoin, a prescription acne medication derived from vitamin A, is strictly contraindicated during pregnancy and should be stopped well before conception.