Ask the expert: How to choose the right prenatal vitamins during pregnancy

If you have ever stood in a pharmacy aisle staring at an overwhelming row of prenatal vitamin bottles, you are not alone. From gummies to capsules, once-a-day formulas to multi-step systems, the choices can feel daunting, especially when the stakes feel so high.

The truth is, prenatal vitamins are one of the most science-backed steps you can take to support a healthy pregnancy, but knowing which ones to take, when to start, and what to look for on the label is something many people who are pregnant or trying to conceive find confusing and at times, overwhelming. 

Questions like “do I need to start before I am pregnant?” or “are these going to make me gain weight?” are common and important.

In this blog, Dr. Li-Shei Lin, MD, a Fertility Specialist at Reproductive Partners Fertility Center in San Diego, and Chacha Miller, a Registered Dietitian Nutritionist at The Cardamom Nutrition, will answer the most commonly asked questions about prenatal vitamins including what prenatal vitamins actually are, what to look for in a good one, when to start taking them, and they clear up some of the most persistent myths along the way.

What are prenatal vitamins? And what prenatal vitamins do?

Chacha Miller: Prenatal vitamins are supplements designed to support both a pregnant person and the developing baby with key nutrients needed for proper growth and development during the gestational period.

I like to think of prenatal vitamins as a sort of safety net or insurance. It is most ideal to get your nutrients from whole foods in the diet, but pregnancy often comes with real challenges like nausea, fatigue, and low appetite. During moments when a pregnant person’s ability to consume adequate nutrients through food is limited, prenatals help fill in those gaps so both mum and baby are still supported.

What is in prenatal vitamins?

Dr. Li-Shei Lin: Prenatal vitamins are intentionally formulated to meet the increased nutritional demands of both the mother and a developing pregnancy. 

What makes them different from a standard multivitamin is the emphasis on key nutrients like folic acid, typically at least 800 micrograms, which is critical in preventing neural tube defects that develop very early in pregnancy, often before someone even knows they are pregnant. 

They also contain higher levels of iron to support the body’s expanding blood volume and increased cardiac output, as well as iodine, which plays a vital role in maintaining healthy thyroid function during a time when metabolism is significantly elevated. 

In many ways, prenatal vitamins are about creating the optimal internal environment for early development from day one.

What ingredients should people look for in a prenatal vitamin?

Dr. Li-Shei Lin: When I counsel patients, I always bring the focus back to three essential nutrients: folic acid, iron, and iodine. 

• Folic acid is the most critical because it supports early fetal brain and spinal cord development, and those processes begin incredibly early, often before a pregnancy is confirmed. 
• Iron is important for preventing anemia as the body adapts to pregnancy. 
• Iodine supports thyroid health, which regulates metabolism and energy use. 

Rather than getting overwhelmed by branding or marketing claims, I encourage patients to look closely at the label and make sure these core nutrients are present in adequate amounts and meet FDA recommended standards.

What are the best prenatal vitamins?

Chacha Miller: Truthfully, there is no single best prenatal. I usually recommend choosing a well-known brand that is third-party tested and includes most of the key nutrients needed to support pregnancy. The best option is the one you can tolerate and take consistently.

Cradlewise note: Third-party testing means an independent organisation, not the manufacturer, has verified that a supplement contains what the label claims and is free from contaminants. Look for certifications from organisations such as USP (United States Pharmacopeia), NSF International, or ConsumerLab when choosing a brand.

When should you start taking prenatal vitamins?

Dr. Li-Shei Lin: The earliest stages of fetal development happen in the first few weeks, so having the right nutrients already in your system can make a meaningful difference. I often tell patients to think of prenatal vitamins as part of preparing your body for pregnancy, not just reacting to it. It is a proactive step that supports both your health and the earliest foundation of a future pregnancy.

Can you take prenatal vitamins without being pregnant?

Dr. Li-Shei Lin: Yes, and in fact, that is exactly when I recommend starting them. Prenatal vitamins are most impactful when taken before pregnancy, not after. I often tell patients to think of prenatal vitamins as part of preparing your body for pregnancy, not just reacting to it. It is a proactive step that supports both your health and the earliest foundation of a future pregnancy.

Is there a best time of day to take prenatal vitamins?

Chacha Miller: There is no perfect time to take a prenatal as it is more about consistency. I often suggest taking them in the morning with food, just to build the habit and help with tolerance.

Cradlewise note: If morning nausea makes it difficult for you to take a prenatal in the morning, try taking it at night with your largest meal of the day. Some people also find that switching from a standard capsule to a gummy formulation during the first trimester helps with tolerance, though it is worth checking that gummy versions still contain iron, as many do not.

What are some tried and tested over the counter prenatal vitamins?

Dr. Li-Shei Lin: Most prenatal vitamins are readily available over the counter and do not require a prescription, which makes them very accessible. Rather than focusing on specific brands, I guide patients to look at the ingredient profile, making sure the vitamin includes adequate levels of folic acid, iron, and iodine and aligns with FDA standards.

A well-formulated prenatal does not need to be complicated. It just needs to consistently deliver the key nutrients that support a healthy pregnancy from the very beginning.

Prenatal vitamins come with their fair share of myths from hair growth to weight gain to fertility boosts. Here, our experts set the record straight on the questions they hear most often.

Will prenatal vitamins help you get pregnant?

Chacha Miller: While taking prenatal vitamins will not necessarily guarantee that you will get pregnant, they can definitely help prepare your body for pregnancy by supporting general nutrient status, which matters for both fertility and early development.

Dr. Li-Shei Lin adds: Prenatal vitamins are not fertility treatments, and they will not increase your chances of conception on their own. However, they play a very important supporting role. Think of them as helping to optimise your body’s baseline health so that when pregnancy does occur, you are starting from the strongest possible foundation. I always emphasise that they are part of a bigger picture that includes nutrition, overall health, and medical care, not a substitute for fertility treatment if that is needed.

How long after taking prenatal vitamins can you get pregnant?

Dr. Li-Shei Lin: There is no specific waiting period after starting prenatal vitamins. You can begin trying to conceive at any time. Their role is not to trigger pregnancy, but rather to ensure your body is nutritionally prepared when it happens. Because early fetal development begins so quickly, having those nutrients on board ahead of time is what really matters.

Can men take prenatal vitamins?

Chacha Miller: Men can take prenatal vitamins, but they are not designed with men’s needs in mind, so it is not something I generally recommend. Some of the nutrients in prenatals, like folate, zinc, and omega-3s, can help support sperm health, but there are starting to be more targeted options out there specifically designed to support men’s reproductive health. 

Additionally, it is important to remember that vitamins are supplemental and are used to fill in nutritional gaps, and they should not replace health-promoting habits like a nutrient-dense diet, regular exercise, and limiting behaviours like smoking or drinking alcohol.

Do prenatal vitamins promote hair growth?

Dr. Li-Shei Lin: There is a persistent myth that prenatal vitamins can improve hair growth, but that is not what they are designed to do. While some individuals may notice changes in their hair, those effects are more often related to hormonal shifts, particularly during pregnancy, rather than the vitamins themselves. Prenatal vitamins are formulated to support fetal development and maternal health, not cosmetic outcomes. It is important to separate those expectations so patients understand their true purpose.

Cradlewise note: Let’s understand the science behind this. During pregnancy, elevated oestrogen levels prolong the hair growth phase, reducing normal shedding and making hair appear thicker and fuller. After delivery, when hormone levels drop, many people experience postpartum hair shedding. The prenatal vitamins are not responsible for either effect.

Do prenatal vitamins make you gain weight?

Dr. Li-Shei Lin: This is a very common concern, but the short answer is no. Prenatal vitamins do not cause weight gain. They do not contain calories or ingredients that would directly impact body weight. What they do provide is a concentrated source of essential nutrients that your body needs, especially when preparing for or supporting a pregnancy. Any weight changes people associate with prenatals are typically due to other factors, not the vitamins themselves.

If you’d like to look up more such articles on our “Ask the expert” series:

• Ask the expert: Pregnancy safety tips every parent should know.
• Ask the expert: What are the early signs of preterm labor, and when should you call your doctor?
• Ask the Expert: How to protect your skin from prenatal sunburn.

Sources:

1. What are prenatal vitamins. Did you know? The American Journal of Clinical Nutrition. 2026. Selecting a dietary supplement with appropriate dosing for 6 key nutrients in pregnancy.
2. What is in prenatal vitamins. Neural tube defects. Spina Bifida Association. 2026. About Spina Bifida. 
3. What is in prenatal vitamins. Spina bifida. CDC. 2025. Neural Tube Defects. 
4. When should you start taking prenatal vitamins. Did you know? CDC. 2025. About Folic Acid. 
5. Can men take prenatal vitamins. Did you know?ScienceDirect. 2018. Diet and men’s fertility: does diet affect sperm quality?