There's an old wives' tale that taking prenatal vitamins will make your hair — and even nails! — grow. But is there any truth to it? Is the lush hair you're experiencing during those nurturing nine months a product of your changing hormones, some additional supplements or both? And if prenatal vitamins do help with hair growth, why aren't more people taking them outside of pregnancy for that reason?

Our experts weighed in on what to make of all the swirling information, plus what's most important when it comes to taking prenatals (spoiler alert: folic acid).

Which ingredients are most important in prenatal vitamins?

All major health organizations recommend you choose a prenatal vitamin with folic acid — at least 400 micrograms. "Folic acid is one of the most important ingredients, as it is necessary for the fetal development of neural tubes and red blood cells," explains Dendy Engelman, M.D., a dermatologist in New York City who goes by Dr. Dendy in her practice. It also plays a role in preventing certain birth defects.” Doctors will recommend that women trying to get pregnant take folic acid at least one month prior to conception, as well as during pregnancy.

"It's also important to discuss with your provider if you are someone with an elevated risk of neural tube defects as you would need a higher dose," says Shannon Smith, M.D., an OB/GYN in Boston, Massachusetts and What to Expect Medical Review Board member. Health conditions like Type 1 or 2 Diabetes, maternal GI malabsorption or a family history or previous history of neural tube defect would mean you might need a higher dose supplement.

The truth about prenatal vitamins and hair growth

It's clear that prenatal vitamins are important for a healthy pregnancy, but if you're looking for them to also help you don luscious locks, there are some things to consider.

Do prenatal vitamins make your hair grow?

This is where things get murky as there is no clear answer. Scroll through TikTok or Instagram and you'll easily find thousands of women who will anecdotally share that prenatal vitamins helped their hair grow during pregnancy. Run this theory by a board-certified doctor, and they'll likely tell you that's not the case.

"There is limited evidence that supports this claim, connecting hair growth to the ingestion of prenatal vitamins," says Dr. Dendy. "While these vitamins do contain the nutrients to support overall health and possibly lead to hair growth, there is no proven direct correlation."

Stefanie Ferraro, a midwife in New York City, echoes this sentiment. "The likelihood that hair and nail growth is due to prenatal vitamins, outside of the pregnancy, is slim," she explains. "Certain vitamins do contain biotin, which some do believe can help hair, skin and nails, but there is limited evidence to support that."

There is, however, one theory that if you were deficient in a certain vitamin or mineral connected to hair health before taking prenatal vitamins, you could get that ingredient into your system from a prenatal vitamin and see your hair grow.

"It is true that when someone starts taking prenatal vitamins they might notice their hair improving and that's because the purpose of taking prenatals is to ensure your body has all the required nutrients for growing a human being," explains Sara Hallajian, a trichologist who specializes in the study and care of hair and the scalp, in Santa Monica, California. "By taking all the necessary vitamins and minerals in prenatal vitamins, you are meeting all of the requirements for our bodies to function," she says. "In return, your hair reaps all the benefits of this uptick in key nutrients, as well. Not everyone experiences this because not everyone has nutritional hair loss prior to starting prenatal vitamins."

What causes hair growth during pregnancy

If your hair does grow thicker during pregnancy, it's a likely side effect of a change in hormones.

"In pregnancy, estrogen influences the growing phase of our hair cycles," Ferraro explains. "In typical hair cycles, hair grows then rests for a few weeks. In pregnancy, the growing part of the cycle is longer — meaning that hair can appear thicker." Essentially your hair is shedding less (due to the influx of estrogen), and you'll have more hair. Interestingly, when you find your hair falling out postpartum, what is actually happening is an estrogen drop, Ferraro notes, and your hair is essentially just returning to how it was prior to pregnancy.

Top ingredients for hair growth found in prenatal vitamins

If you're deficient in a vitamin or mineral that contributes to hair health, then here are some common ingredients to look for in prenatal vitamins that could help with hair growth, in addition of course to the nutrients they provide for both you and your baby.

Ingredient: Folic Acid

What it does: Essential for red blood cell formation and lowering the risk of neural tube defects, according to Dr. Dendy.

How it affects hair growth: "Indirectly supports healthy hair growth through the production of keratin," says Dr. Dendy.

If you're deficient in folic acid, it can hinder hair growth and even cause hair loss, adds Gretchen Friese, a trichologist for BosleyMD. "So taking the supplement if you are deficient can help hair growth. But only if you are deficient."

Ingredient: Iron

What it does: Crucial for carrying oxygen in the blood and preventing anemia during pregnancy, notes Dr. Dendy.

How it affects hair growth: "Iron deficiency can lead to hair loss, so it's crucial to maintain optimal iron levels," the dermatologist explains.

Hallajian adds, "Iron helps our cells function properly and our hair is not vital to survival, so if our bodies are deficient in iron our hair will lack healthy cells and break easily."

Ingredient: Vitamin D / D3

What it does: Important for calcium absorption, bone health, and immune function, according to Dr. Dendy.

How it affects hair growth: "Vitamin D receptors are found in hair follicles," explains Dr. Dendy.

"It helps cells in dermal papilla grow new hairs and it's anti-inflammatory," notes Hallajian.

Should you take prenatal vitamins for hair growth even when you aren't pregnant?

In most cases, your body does not need the high level of minerals in these vitamins outside of pregnancy so they would exit your body as waste, explains Dr. Dendy. "In other cases, however, high concentrations of certain minerals found in prenatal vitamins can cause unwanted side effects like nausea and constipation in those who are not pregnant," she adds, recommending women who are not pregnant or trying to conceive skip prenatal vitamins to avoid these risks.

What to take, instead of prenatal vitamins, for hair growth

It’s a good idea to work with a healthcare provider to identify the vitamins and supplements that would be best for your lifestyle and health concerns, explains Dr. Dendy.

"For hair growth, I recommend B vitamins (including biotin), keratin, magnesium, and calcium," she says. "For nail growth, I would recommend taking B vitamins (including biotin), iron and vitamins A and C."

Friese also suggests collagen, niacin and zinc to help keep your scalp, and thus your hair, healthy. Some studies show that these nutrients may help maintain normal hair growth and lead to thicker, fuller hair. Still, it's challenging to prove any of these ingredients will do the trick.

"It's important to see a specialist to get a deeper understanding of your hair changes before taking something new, crossing your fingers, and wasting your money,” says Hallajian.

The bottom line on prenatals for hair growth? There is no evidence supporting the fact that prenatal vitamins will make your hair grow. Whether you're trying to conceive, pregnant or postpartum, collaborate with your healthcare provider on your supplement regimen — and remember, hormones are likely the cause of all those hair changes during pregnancy. No magic pill or gummy can change this biological process.