Do prenatal vitamins improve fertility? Yes, studies say.
Last updated April 07, 2021
The standard advice among OBGYN doctors is that women who are actively trying to conceive should be taking prenatal vitamins, even if they aren’t pregnant just yet. This is partially because at the very early stage of pregnancy, when the crucial organs of the fetus—like the neural tube—are being formed, we usually don’t know that we are pregnant. So, to ensure that the baby has all the nutrients s/he needs from the very beginning of life, doctors recommend that women start taking prenatal vitamins when they start trying - ideally, at least 3 months of prenatal vitamins is recommended before pregnancy. (Then, once pregnant, women should stay on prenatal vitamins until they deliver – or even better, until they finish breastfeeding.)
But do prenatal vitamins also improve your chance of getting pregnant?
Interestingly, studies have found that, yes, women who take prenatal vitamins are more likely to achieve pregnancies than those who don’t. A large, 8-year-long follow-up study of over 18,000 women without a history of infertility found a significantly lower risk of ovulatory infertility among women who consistently took multivitamin supplements, compared to women who didn’t. The relative risk decreased with increasing adherence to the supplementation schedule, suggesting a dose-dependent effect.
A 2019 review that examined existing studies on micronutrient status of women attempting pregnancy summarizes the current understanding of prenatal vitamins and fertility:
- For women who have vitamin deficiencies, taking prenatal vitamins before conception can restore micronutrient status to the recommended levels;
- It may also reduce oxidative stress, when the prenatal vitamins include antioxidants;
- Prenatal vitamins have a small but beneficial effect on fertility in both healthy women and women having difficulty conceiving; and
- Women taking prenatal vitamins are more likely to get pregnant, and in a shorter period of time.
Vitamins with fertility prowess
As the review’s authors noted, well-designed studies (like prospectively randomized controlled trials, the gold standard in scientific research) investigating the fertility effects of multiple nutrients is rare. Studies looking at each nutrient separately, or a combination of just a few, are more abundant. Here’s what we know about the fertility-related functions of the common vitamins and minerals found in prenatal vitamins.
Vitamin C and Vitamin E
Vitamin C and Vitamin E, both antioxidants, have been found to play a major role in female reproductive process.
- Both of these vitamins protect eggs (and sperm, for that matter) from DNA damages due to oxidative stress.
- For example, Vitamin E has been shown to reduce DNA fragmentation and encourage healthy development of embryos, while reducing risks of preeclampsia and other pregnancy complications for the mom. (Here’s a review of the current state of science on Vitamin E.)
Vitamin D is one of the most actively studied micronutrients in the fertility context.
- Multiple studies have found that vitamin D deficiency is more common in women with PCOS than their healthy counterparts.
- Women with PCOS and low vitamin D levels have also been found to have poorer outcomes when they undergo ovarian stimulation for fertility treatment.
- While the mechanisms of action need further investigation, one 2013 review hypothesized that this may be because vitamin D directly impacts AMH production and protects ovarian reserve from deteriorating.
- Even among otherwise healthy women, those who met the daily recommended level of vitamin D and whose serum levels were adequate (over 50 nmol/L) were significantly more likely to become pregnant and deliver a healthy baby.
B vitamins have been identified as a significant contributor in the reduction of ovulatory infertility risks, in the cohort study of 18,000+ women over 8 years, mentioned earlier.
- Another study analyzed the serum levels of vitamin B-12 and outcomes of 154 fertility treatment cycles, and found that women in the highest quantile for vitamin B-12 levels were more than twice as likely to have a live birth, compared to women in the lowest quantile.
- How B vitamins contribute to reproductive success is still not completely understood, but one strong hypothesis relates to its ability to reduce homocysteine, an amino acid that negatively impacts embryo quality.
Folate (also a B vitamin)
Folate (folic acid) appears to facilitate healthy reproductive process in multiple ways.
- A Danish study found that folic acid supplementation was linked to higher fertility rates.
- Similar to the B vitamins, folate/folic acid is thought to reduce homocysteine, potentially contributing to the findings that women taking folic acid before IVF have more mature, better-quality eggs.
- Furthermore, folate supplementation has been shown to support optimal progesterone level and reduce the risk of anovulation.
Bottom line on prenatal vitamins for fertility
As mentioned earlier, there aren’t quite enough well-designed studies investigating the fertility benefits of using multi-nutrient supplements to know for sure that prenatal vitamins can increase the chance of pregnancy. One likely confounding factor: It’s possible that women who take prenatal vitamins during the preconception period are more informed about nutritional needs and have generally healthier habits, which may contribute to the observed effects.
While some of the nutrients commonly found in prenatal vitamins have a significant evidence in the literature regarding their ability to facilitate conception, research is still needed to understand why they work.
That said, it’s still true that women planning to get pregnant in the near future should take prenatal vitamins before they get pregnant. That’s the recommendation of the American College of Obstetricians and Gynecologists, as well as ours. If that gives you an extra fertility boost, more power to the vitamins!
Next week, we'll review the state of science on some minerals' involvement in our reproductive process. Reach out with any questions – we are with you.
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