The supplements most strongly linked to improved fertility target a few core processes: egg quality, ovulation regularity, sperm health, and the nutritional foundation needed to sustain a pregnancy. What you should take depends on whether you’re trying to improve female fertility, male fertility, or both, and the benefits take time to show up. Most fertility supplements need at least three months of consistent use before they meaningfully affect egg or sperm development.
Why Three Months Is the Minimum
Sperm take roughly 72 to 90 days to fully develop, so any supplement targeting male fertility won’t show results in a semen analysis for about three months. On the female side, the final stages of egg maturation span a similar window. Clinical trials on fertility supplements almost universally run for 12 weeks or longer for this reason. Starting supplements well before you plan to conceive, ideally three to six months ahead, gives them the best chance of working.
CoQ10 for Egg Quality
Coenzyme Q10 is the supplement with the most direct evidence for improving egg quality, particularly in women over 35 or those with diminished ovarian reserve. Eggs are among the most energy-demanding cells in the body, and CoQ10 fuels the cellular machinery that powers them. As you age, natural CoQ10 levels drop, which is one reason egg quality declines.
Clinical trials have used doses ranging from 180 mg to 1,200 mg per day, with 600 mg daily for at least two months being the most commonly studied regimen. At that dose, women under 35 with poor ovarian reserve doubled their egg retrieval numbers (four eggs versus two in the control group) and saw fertilization rates jump from 45% to 67%. Women undergoing IUI cycles on 600 mg daily had higher follicle counts and more mature follicles. Even a lower dose of 180 mg per day increased the number and size of mature follicles when used alongside ovulation-stimulating medication.
Inositol for PCOS-Related Infertility
If irregular ovulation or polycystic ovary syndrome is part of the picture, myo-inositol is the most well-studied supplement. It improves insulin sensitivity, which is the metabolic issue driving most PCOS symptoms, and helps restore regular ovulation. The key detail is the ratio: clinical evidence supports combining myo-inositol with D-chiro-inositol in a 40:1 ratio, which mirrors the natural proportion found in the blood of women without PCOS. In one trial, obese women with PCOS who took this combination for six months showed improved insulin sensitivity and ovulatory function. Many fertility-focused inositol products already use this ratio, but it’s worth checking the label.
Folate: Which Form Matters
Folate is non-negotiable for anyone trying to conceive. It dramatically reduces the risk of neural tube defects when taken around the time of conception, which is why starting before pregnancy matters. The standard recommendation is at least 400 mcg daily from a prenatal vitamin.
Here’s the less commonly known detail: roughly 40% to 60% of people carry genetic variations that impair the body’s ability to convert standard folic acid into its usable form, L-methylfolate. If you have a family history of neural tube defects or preterm births, choosing a prenatal vitamin containing L-methylfolate instead of folic acid bypasses that conversion step entirely. For everyone else, standard folic acid works fine. Either way, a good prenatal vitamin with adequate folate, iron, and vitamin B12 forms the baseline of any fertility supplement plan.
Vitamin D and Pregnancy Rates
Vitamin D deficiency is remarkably common, and it has a measurable effect on conception. A large prospective study of over 1,100 women found that those with sufficient vitamin D levels (at or above 30 ng/mL in blood) were 15% more likely to achieve a live birth and 10% more likely to achieve clinical pregnancy than women with lower levels. This held true even after adjusting for other factors like age and BMI.
Getting your vitamin D level tested is straightforward and inexpensive. If you’re below 30 ng/mL, supplementation with vitamin D3 can bring levels up over the course of a few months. Many prenatal vitamins contain some vitamin D, but often not enough to correct a deficiency on their own.
Supplements for Male Fertility
L-Carnitine
L-carnitine has the strongest evidence base among male fertility supplements. It fuels the energy production that sperm need for motility, and it protects sperm membranes from oxidative damage. Trials consistently show improvements in sperm motility, concentration, and morphology at doses of 1 to 3 grams per day taken for three to six months. One study using 3 grams daily for three months found significant improvements in the percentage of motile sperm and normally shaped sperm. Another trial combining 2 grams of L-carnitine with 1 gram of acetyl-L-carnitine daily for six months reported improvements across all sperm parameters.
There’s also a direct correlation between L-carnitine concentrations in seminal fluid and sperm count and motility, which suggests that men with lower baseline levels may see the largest benefit.
Antioxidant Combinations
Oxidative stress is one of the most common treatable causes of poor sperm quality. Sperm are especially vulnerable to it because of their high concentration of fragile fatty acids in their membranes. A combination approach tends to work better than any single antioxidant.
One multicenter study gave men a blend of myo-inositol, alpha-lipoic acid, CoQ10, zinc, selenium, folic acid, and B vitamins for 12 weeks. Sperm DNA fragmentation, a key marker of sperm health that standard semen analyses miss, dropped from 28% to 16%. The most commonly studied individual components for male fertility include zinc (15 to 20 mg daily), selenium (55 to 200 mcg daily), vitamin C (500 mg daily), and vitamin E (400 mg daily). These work by neutralizing the reactive molecules that damage sperm DNA and cell membranes.
That said, not every trial shows dramatic results. One large randomized controlled trial using a similar antioxidant combination for three months found only modest, statistically insignificant differences in DNA fragmentation between the supplement and placebo groups. The takeaway: antioxidants likely help, but they’re not a guaranteed fix, and results vary depending on whether oxidative stress was actually the underlying problem.
What to Skip or Approach Carefully
Herbal supplements like vitex (chasteberry) are widely marketed for fertility, but the clinical evidence is far thinner than what exists for the supplements listed above. Vitex can also interact with hormonal medications, including those used in fertility treatments, making it a poor choice if you’re working with a reproductive endocrinologist.
Prenatal and fertility supplement blends can interact with a surprisingly long list of medications. Common interactions include blood thinners, thyroid medications, certain antibiotics (particularly tetracyclines and fluoroquinolones), blood pressure medications, and antiseizure drugs. The minerals in these supplements, especially iron, calcium, and zinc, can block absorption of other medications if taken at the same time. If you’re on any prescription medication, spacing your supplements at least two hours apart from your medication is a simple way to reduce this risk.
Putting a Plan Together
For women, a reasonable evidence-based stack looks like: a quality prenatal vitamin with folate (or methylfolate if you have risk factors), CoQ10 at 200 to 600 mg daily, vitamin D3 if your levels are low, and inositol in a 40:1 myo-to-DCI ratio if PCOS is involved. For men, L-carnitine at 1 to 2 grams daily combined with a broad antioxidant that includes zinc, selenium, and CoQ10 covers the most well-supported bases.
Start at least three months before you want to conceive, and stay consistent. Supplements work cumulatively, not overnight. The ones with the best evidence target specific, measurable biological processes, not vague claims about “reproductive wellness.” If you’ve been trying to conceive for over a year (or six months if you’re over 35), supplements alone are unlikely to resolve the issue, and a fertility evaluation can identify problems that no supplement can fix.