Importance, Types, and Side Effects

Prenatal vitamins contain special formulations of essential vitamins and minerals like folic acid (folate), calcium, and iron which your body needs more of while carrying a developing baby.

Whether you’re trying to conceive or just found out you are pregnant, prenatal vitamins, also known as prenatal supplements, can help fill in any nutritional gaps in your diet to help support a healthy pregnancy.

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If you’ve started shopping around for prenatal supplements, you already know there are a slew of options to choose from, and it is possible to take too much or too little of certain nutrients depending on your health history and needs.

Before you stock up on prenatal vitamins and supplements, contact your healthcare provider, doctor, or midwife to determine the best option for you.

In the meantime, learn why prenatal vitamins are important, the different types to choose from, and how to deal with potential side effects.

When to Take Prenatal Vitamins

Although the term prenatal (meaning “before birth”) might make it sound as if these supplements are only to be taken during pregnancy, for your health and the health of your baby you should ideally take prenatal vitamins at least one month before you conceive, during pregnancy, and postpartum while breastfeeding. 


Prenatal vitamins help ensure your body has the nutrients it needs to keep you healthy throughout pregnancy and support the proper growth and development of your baby.

Along with a nutritious diet and regular exercise (as long as you have the OK from your doctor), prenatal supplements can increase your chances of creating the ideal environment for a growing baby.  

Folic acid supplements are especially important to reduce the risk of neural tube defects (NTDs). These are serious problems with the baby’s development of the neural tube, the precursor to the brain and spinal cord. For this reason, it’s best to begin taking prenatal vitamins containing folic acid at least one month before trying to conceive.

In fact, because a baby’s neural tube develops during the first month of pregnancy—before many people even know they’re pregnant—the American College of Obstetricians and Gynecologists (ACOG) encourages all women of reproductive age to regularly take folic acid supplements to reduce the risk of NTDs.

If you’re at an increased risk of NTDs due to a family history of spina bifida or certain anti-epileptic medications, for example, you’ll want to begin taking greater amounts of folic acid even earlier, per the ACOG.


Prenatal vitamins come in the form of pills, capsules, gummies, and liquids which can be organic or vegan. You can buy many prenatal vitamins over-the-counter, though some are only available with a prescription from your healthcare provider. 

There’s no one-size-fits-all prenatal supplement ,and it is possible to harm your health or your baby’s by taking inappropriate amounts of some synthetic vitamins. Again, be sure to consult with your doctor before taking them on your own.

Most prenatal vitamins contain the following nutrients to support your baby’s health and development.

Folic Acid

Folic acid (folate) helps reduce the risk of NTDs such as spina bifida. People trying to conceive should take 400 to 800 micrograms (mcg) of folic acid per day through diet and supplements at least one month before becoming pregnant.

Those at an increased risk of NTDs should take 4,000 mcg of folic acid per day one month before becoming pregnant and through the first three months of pregnancy, per the Centers for Disease Control and Prevention (CDC).

The CDC recommends all women of reproductive age take 400 mcg of folic acid daily to prevent NTD. Many multivitamins contain this amount of folic acid, but it’s important to check the specific vitamin’s nutrition label. Most prenatal vitamins contain 800 mcg of folic acid.


Iron provides the building blocks needed for red blood cells, which deliver oxygen to your growing baby. During pregnancy, you need 27 milligrams (mg) of iron per day (nearly twice the daily recommended intake for women who aren’t pregnant).


Calcium helps keep your bone density up as your baby uses the mineral to grow and develop. You need 1,000 mg of calcium per day (or 1,300 mg if you’re 18 or younger). Prenatal vitamins generally contain 200 mg to 300 mg as a supplement to your diet to ensure you reach your daily needs. 

Other Vitamins and Minerals

Some types of prenatal vitamins may also include the following vitamins and minerals: 

  • Docosahexaenoic acid (DHA): This type of omega-3 fatty acid supports your baby’s brain and eye development. 
  • Iodine: This mineral supports the development of your baby’s brain and nervous system. While pregnant, you need 220 mcg of iodine each day.
  • Choline: This nutrient is key for your baby’s developing brain and spinal cord. It’s recommended that people who are pregnant get 450 mg a day. 
  • Vitamin A: This vitamin helps form healthy skin, eyes, and bones and is involved in immune function. Doctors recommend that you get in 770 mcg each day (or 750 mcg if you’re 18 or younger).  
  • Vitamin C: This vitamin supports healthy gums, teeth, and bones. You need 85 mg total each day (or 80 mg if you’re 18 or younger). 
  • Vitamin D: This vitamin also helps your baby grow teeth and bones. People who are pregnant need 600 international units (IU) per day. 

The optimal balance of vitamins and minerals can vary depending on your health history, diet, and nutritional needs, so talk to your healthcare provider before choosing one type of prenatal supplement over another. 

Side Effects 

Unfortunately, prenatal vitamins can come with side effects, some of which are (confusingly) also common side effects of pregnancy, such as nausea and constipation.

If you experience concerning side effects while taking prenatal vitamins, contact your healthcare provider. You may be able to try a different brand or type of supplement, or adjust when and how you take them, to ease side effects.

The most common source of side effects in prenatal supplements is iron, which can cause constipation as well as other gastrointestinal side effects including:

  • Nausea 
  • Flatulence
  • Abdominal pain or upset stomach
  • Diarrhea 
  • Black or tarry stools

If you’re unable to adjust your dosage or supplement type, your doctor may advise you to make lifestyle changes to get your digestive system going again. The following can sometimes help ease constipation: 

  • Drink more water 
  • Add more fiber-rich foods to your diet like whole grains, fruits, and vegetables 
  • Incorporate movement or exercise into your daily routine
  • Consider a stool softener 

Otherwise, keep an eye out for signs of an allergic reaction. 

Call your healthcare provider immediately if you experience signs of an allergic skin reaction such as raised bumps or hives, itchiness, redness, swelling, or cracked, scaling, or flaking skin.

A Word From Verywell 

If you’re trying to conceive or just discovered you’re pregnant, it’s normal to experience waves of so many different emotions—excitement, dread, fear, grief, joy, and more.

Now, one of the best things you can do for yourself and your baby is to contact a healthcare provider as soon as possible to figure out the next steps and determine the best prenatal vitamin or supplements for you.

Along with a healthy diet and lifestyle, a prenatal supplement can ensure you’re giving your body everything it needs to support you and your developing baby throughout pregnancy and the early days of parenthood.