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Supplements for Fertility When You're Trying to Conceive: Folic Acid, CoQ10, Inositol and What the Trials Show

For women trying to conceive, folic acid is the one supplement with strong evidence: 400 to 800 mcg a day, from at least a month before conception, lowers the baby's risk of spine and brain defects (grade A). CoQ10, myo-inositol, melatonin and NAC have not clearly raised live births (grade C). Tell your fertility team about every supplement, and don't let supplements delay a check-up: after 12 months of trying under 35, 6 months over 35, straight away over 40.

Published How we grade evidenceEditorial policy

This guide is for women trying to conceive, naturally or with fertility treatment such as IVF (in vitro fertilisation). For the male partner, see supplements for low sperm count.

Start folic acid now, tell your fertility team about every supplement, and don't use a supplement in place of a fertility check-up. Get checked after 12 months of trying if you are under 35, after 6 months if you are over 35, and straight away over 40 or with a condition known to affect fertility (ACOG 2019).

The short version

  • Folic acid, from before conception: it cut neural tube defects (spine and brain defects) in babies, though it is for the baby, not for getting pregnant. Grade A (De-Regil 2015; USPSTF 2023).
  • CoQ10 before IVF (women with low ovarian reserve): more clinical pregnancies in small, loosely reported trials, but more babies born has not been shown. Grade C (Lin 2024; Xu 2018).
  • Myo-inositol, melatonin and antioxidant mixes in fertility treatment: reviews rate the evidence for live births low or very low, and several of their trials have since been retracted. Grade C (Showell 2018; Showell 2020).
  • Vitamin D before IVF (women with PCOS): blood levels doubled, live births did not change. Grade B (Hu 2026).
  • DHEA for poor responders to IVF: little or no difference in live births, and it is a hormone. Grade B (Naik 2024).
Supplement (who, compared with what)What trials foundSize of effectGrade
Folic acid (women around conception, vs none or placebo)Lower neural tube defect rateRisk ratio 0.31 (5 trials, 6,708 births)A
CoQ10 (IVF, women with low ovarian reserve, vs placebo or nothing)More clinical pregnancies in small trials with poorly described methods; more births not shownOdds ratio 1.84 for clinical pregnancy (6 trials, 1,529 women)C
Myo-inositol (PCOS, IVF, vs standard care)Live births uncertain2 trials, 84 womenC
Vitamin D (PCOS, before IVF, vs placebo)No more live births52.0% vs 50.2% (865 women)B
DHEA (poor IVF responders, vs placebo or nothing)Little or no difference in live birthsOdds ratio 1.30 (9 trials, 1,433 women)B

Which supplements should you take when trying to conceive?

Folic acid, grade A for protecting the baby. The US Preventive Services Task Force recommends 400 to 800 mcg (0.4 to 0.8 mg) of folic acid every day for anyone planning or able to get pregnant, started at least 1 month before conception and continued through the first 2 to 3 months (USPSTF). Pooling 5 trials (6,708 births), Cochrane reviewers found folic acid cut the rate of neural tube defects (risk ratio 0.31) on high-quality evidence, with no change in miscarriage (De-Regil 2015). If you, your partner or your family have had a neural tube defect, you've had bariatric surgery, or you take seizure medicine, USPSTF says to talk with your clinician first, because these raise the risk. More detail is in our prenatal supplements guide.

A multivitamin: grade C. In 2,370 couples seeking fertility treatment, women who used a multivitamin had more live births (adjusted risk ratio 1.22), but only couples who had no treatment showed the link, folic acid alone showed none, and this was an observational analysis, not a test of the vitamin (Sealy 2026). Check that any prenatal you pick keeps vitamin A low (see Safety).

Does CoQ10 help egg quality?

Grade C: more eggs and more clinical pregnancies in small IVF trials, but more babies born has not been shown. In 169 women under 35 with low ovarian reserve (few eggs left), CoQ10 for 60 days before IVF gave more eggs, more top-quality embryos and fewer cancelled transfers than no pre-treatment; pregnancies and live births trended higher but not significantly (Xu 2018). Pooling 6 trials (1,529 women with low ovarian reserve), CoQ10 before IVF raised the clinical pregnancy rate (odds ratio 1.84) and the number of eggs collected; its authors flag small samples and poorly described methods (Lin 2024). An earlier, more widely quoted pooling leaned on a PCOS trial that has since been retracted, so its pregnancy figure is not used here (retraction notice). Let your fertility team set any amount. For CoQ10 with warfarin or blood pressure medicine, see CoQ10 supplements.

Does inositol help you get pregnant?

Grade C: uncertain for pregnancies and births. A Cochrane review of 13 trials (1,472 women with polycystic ovary syndrome, or PCOS) mostly tested myo-inositol before IVF. The quality was low to very low; live births could not be judged (2 trials, 84 women), and a drop in miscarriage rested mainly on one study with an unusually high miscarriage rate in its control group (Showell 2018). Two trials of this comparison have since been retracted, one probably the study behind that drop, so even this weak evidence is weaker than it looks (retraction notice). The inositol page shows C, "improves", from three small egg-quality trials; for births, this review says the evidence is too weak to tell. For irregular periods and ovulation in PCOS, see supplements for PCOS.

Is inositol safe while trying to conceive? Its side effects in PCOS trials were mostly mild stomach upsets (Fitz 2024). Trials in pregnancy started at 10 to 24 weeks and measured few baby outcomes (Motuhifonua 2023), so once you are pregnant, ask your midwife or obstetric team whether to continue.

Does NAC help fertility?

Grade C: no clear effect on pregnancy. Pooling 15 trials (2,330 women, mostly with PCOS or unexplained infertility), N-acetylcysteine (NAC) added to fertility drugs did not clearly raise clinical pregnancy (odds ratio 1.55, range 0.98 to 2.47) or ovulation, and it did worse than metformin (Devi 2020). This review's trial list includes three trials that have since been retracted, two of NAC with clomiphene and one after ovarian drilling, so even this null result overstates the evidence (retraction notices, 2, 3); an earlier positive review also pooled one of them (Thakker 2015).

Does vitamin D help fertility or IVF?

Grade B: no more live births. In a double-blind trial of 876 women with PCOS (865 analysed), vitamin D for up to 90 days before IVF lifted blood levels from about 16 to 32 ng/mL, but live births after the first embryo transfer were 52.0% against 50.2% on placebo (Hu 2026). Pooling 5 earlier trials in women with low vitamin D, clinical pregnancies did not clearly rise (Zhou 2022). If a blood test shows you are low, your clinician can treat that; see vitamin D supplements.

Does melatonin help IVF?

Grade C: no clear gain in pregnancies or births. An 11-study pooling concluded that melatonin during IVF may not significantly improve clinical pregnancy or live birth rates (live births were measured in only 3 studies), though it may help egg and embryo quality (Tang 2025). The largest trial in that pooling, of myo-inositol plus melatonin in women with PCOS, was retracted in 2026, so its overall figures are not used here (retraction notice). Use it only if your IVF clinic agrees; its other effects are covered in sleep supplements compared.

Do antioxidants help female fertility?

Grade C, very low certainty. A Cochrane review of 63 trials (7,760 women) tested antioxidants from NAC and melatonin to vitamins C, D and E, CoQ10 and omega-3. Live births looked higher (odds ratio 1.81, 13 trials, 1,227 women), but the reviewers were uncertain because the evidence was very low quality; miscarriage did not differ, and only 27 trials said who funded them (Showell 2020). Seven trials in this review have since been retracted and two more carry expressions of concern; Cochrane's editors say removing them does not meaningfully change its findings. A 2024 umbrella review found that multiple micronutrient and antioxidant mixes went with more live births (odds ratios 2.59 with fertility treatment and 1.81 when trying naturally), and several single supplements with more clinical pregnancies, but rated every one of these pregnancy and birth results very low certainty (Pandey 2024).

Should you take DHEA for IVF?

Grade B: little or no difference in live births. DHEA (dehydroepiandrosterone) was tested mostly in women who respond poorly to IVF drugs. The 2024 Cochrane update of 28 trials found little or no difference in live births or ongoing pregnancies (odds ratio 1.30, 9 trials, 1,433 women) and no fewer miscarriages, on moderate-certainty evidence (Naik 2024); at least one trial in its reference list that favoured DHEA has since been retracted, so the true effect may be smaller still. The 2015 version had found a benefit that shrank and lost significance when trials at high risk of bias were dropped (Nagels 2015).

DHEA is a hormone your body converts to testosterone and oestrogen, so it can shift sex hormone levels. It can cause acne and oily skin, and in women, hair growth on the face and body. Don't take it with a current or past hormone-sensitive cancer (breast, ovarian or endometrial), or while pregnant or breastfeeding. In the UK, Canada and Australia it needs a prescription or is a controlled drug, and tested sport bans it as an S1 anabolic agent on the World Anti-Doping Agency list (WADA). Use it only under your fertility team. See DHEA.

What about the male partner?

A fertility check-up should include the male partner too. For what supplements do for sperm, see supplements for low sperm count and the fertility section of CoQ10 supplements.

What we'd skip

  • Fertility blends with high-dose vitamin A (retinol): in a study of pregnant women, those whose supplements gave them more than 10,000 IU of preformed vitamin A a day had 4.8 times the rate of some birth defects, mostly when taken before week 7 (Rothman 1995).
  • DHEA on your own: no clear gain in live births (Naik 2024), plus the hormone side effects in the DHEA section above.
  • NAC to get pregnant: no clear effect in 15 pooled trials, three of which have since been retracted (Devi 2020).
  • Stacks sold to "improve egg quality": most trials measured egg and embryo counts; where pooled results showed more births, the evidence was very low certainty, too weak to rely on (Pandey 2024).

Safety and interactions

  • Vitamin A: the adult upper limit is 3,000 mcg (10,000 IU) of preformed vitamin A daily, as higher intakes can cause birth defects and liver damage; while trying to conceive, stay under it unless your midwife or obstetric team says otherwise (NIH ODS; check your stack). Beta-carotene from plants does not count toward it.
  • Folic acid: upper limit for adults, 1,000 mcg a day from supplements and fortified foods, because higher amounts can hide a vitamin B12 deficiency; go above it only on a prescription or your obstetric team's advice (NIH ODS).
  • DHEA: a hormone with the cautions above; never in pregnancy.
  • CoQ10: may weaken warfarin; see CoQ10 supplements.
  • Thyroid medicine: if you take levothyroxine, see supplements and thyroid medicine for what to space from it. Iodine needs for pregnancy are in the prenatal guide.
  • Fertility treatment: clinics want to see every supplement you take before a cycle starts. Bring the bottles.
  • Once you're pregnant: your midwife or obstetric team decides what to continue; this guide gives no amounts for pregnancy beyond folic acid.

When to see a doctor

  • Book a fertility check after 12 months of trying under 35, after 6 months over 35, and straight away over 40 (ACOG 2019).
  • Go sooner with absent or very irregular periods, known PCOS or endometriosis, painful periods or pelvic pain, past pelvic infection or surgery, repeated miscarriages, or a partner with known sperm problems.
  • Get emergency care for sharp pain on one side of the lower belly, shoulder-tip pain, fainting or heavy bleeding with a positive test or a late period (possible ectopic pregnancy).

Don't stop a prescribed medicine on your own; ask the prescriber or pharmacist. Once pregnant or while breastfeeding, follow your midwife or obstetric team. Under 18? Ask a clinician.

FAQ

Does CoQ10 improve egg quality? In small IVF trials in women with low ovarian reserve it raised egg counts and clinical pregnancies, but more babies born has not been shown (grade C) (Lin 2024; Xu 2018). Take it only with your fertility team.

How long does CoQ10 take to work for fertility? The clearest trial gave it for 60 days before IVF in women under 35 with low ovarian reserve (Xu 2018). No trial has shown how long it takes to raise live births.

Is inositol safe to take while trying to conceive? Side effects in PCOS trials were mostly mild stomach upsets (Fitz 2024), but its effect on births is uncertain (grade C) (Showell 2018). Once pregnant, ask your midwife or obstetric team whether to continue.

Does NAC help you get pregnant? Pooled trials found no clear rise in pregnancy or ovulation (grade C), and three of those trials have since been retracted (Devi 2020).

Should I take prenatal vitamins before trying to conceive? Folic acid, yes: 400 to 800 mcg a day from at least a month before conception through the first 2 to 3 months of pregnancy lowers the baby's risk of neural tube defects (grade A) (USPSTF 2023). A multivitamin was linked to more live births in one observational study (grade C) (Sealy 2026).

Sources

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