What Do Prenatal Vitamins Contain?

If you’re pregnant or trying to conceive, your doctor has probably recommended that you take a prenatal vitamin. These can meet the higher demand for certain nutrients needed to support a healthy pregnancy and growing baby. Here’s a look at what is in a prenatal vitamin and why the nutrients in prenatal vitamins are so important.

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Nutrients in Prenatal Vitamins

Good nutrition is crucial during pregnancy. The nutrients you get from your diet keep you healthy and help your baby grow and develop. Most of your nutrition should come from a healthy diet, but prenatal vitamins can help close any gaps in your diet.

Prenatal vitamins can vary somewhat in the types of nutrients they provide. But generally, compared to regular daily vitamin and mineral supplements, they have higher amounts of several key nutrients. These play a vital role in helping your baby grow and develop normally.

Folic acid

You need higher amounts of most B vitamins during pregnancy, but folic acid is the most important B vitamin. It’s essential for making the healthy red blood cells, DNA, and proteins your baby needs.

Folic acid is also crucial for your baby’s brain and nervous system development. Supplementing with folic acid reduces the risk of brain and spinal cord abnormalities known as neural tube defects. Taking folic acid may also help reduce the risk of birth defects in your baby’s heart and mouth.

  • Before pregnancy, take a vitamin that provides at least 400 mcg of folic acid.
  • During pregnancy, take a prenatal vitamin that has 600 mcg of folic acid.


You need iron to make hemoglobin, the protein in red blood cells that carries oxygen throughout your body. During pregnancy, your blood volume — and the need for red blood cells — increases. That extra blood delivers oxygen and nutrients to your baby. Anemia (low red blood cells) is common in pregnancy and taking an iron supplement helps to prevent this.

Women of childbearing age need 18 mg of iron each day. But when you’re pregnant, you need 27 mg of iron each day. A prenatal vitamin provides that extra amount.


Calcium helps your baby develop strong bones and teeth. You and your baby also need it for your nerves, muscles, and heart to work normally. You need 1,000 mg of calcium daily before, during, and after pregnancy, and a prenatal vitamin can ensure you get enough.

It’s crucial to get enough calcium during pregnancy. If you don’t get enough from diet or supplements, your body pulls it from your bones to meet your baby’s needs. That can increase your risk of osteoporosis later in life.

Vitamin D

Vitamin D helps your body absorb calcium so your baby’s skeletal system can develop normally. This vitamin also supports your immune system, and it helps regulate your blood pressure. Supplementing with vitamin D may help prevent preeclampsia, a condition where a pregnant woman’s blood pressure gets dangerously high.

Your body makes vitamin D from sunlight exposure, but you may not make enough in the winter months. A prenatal vitamin can guard against low levels. It supplies the 600 IU (international units) of vitamin D you need every day.


Iodine is a mineral that helps make thyroid hormones and helps your baby’s nervous system develop normally. You can get iodine from your diet, especially fish, dairy foods, and eggs. But you may not get enough if you eat a plant-based diet.

Not all prenatal vitamins provide iodine, so ask your doctor if you should take one that does. Pregnant women need 220 mcg of iodine each day.


DHA is an essential omega-3 fatty acid found in fatty fish and fish oil. It plays a significant role in your baby’s brain and eye development, but not all prenatal vitamins contain DHA, or they may not provide enough.

You can get adequate DHA if you eat eight to 12 ounces of low-mercury, oily fish (like salmon and sardines) each week. If you don’t eat any or enough fish, ask your doctor if you should take a prenatal vitamin with DHA. Pregnant women should aim for at least 220 to 300 mg of DHA.

When to Start Taking Prenatal Vitamins

You should certainly take a daily prenatal vitamin once you have a positive pregnancy test. But if you’re trying to conceive, doctors recommend starting prenatal vitamins at least three months before you want to pregnant. This optimizes your nutrition to give your growing baby the best start possible.

The most important reason to start a prenatal vitamin before you get pregnant is to boost your folic acid levels. Many people don’t find out they’re pregnant until well into their first trimester, when their baby’s spinal cord is already developing. Getting the extra folic acid you need before you even conceive reduces the risk of neural tube and birth defects.

It’s essential to talk to your doctor about folic acid and prenatal vitamins if you are contemplating pregnancy and:

  • You’ve had a baby with a spinal cord (neural tube) defect.
  • You or your partner has a neural tube defect.
  • Your partner has a child with a neural tube defect.
  • You have a seizure disorder for which you take medication.
  • You have a medical condition such as sickle cell disease, celiac
    disease, inflammatory bowel disease, or have had a bariatric surgery like
    gastric bypass.

Your health care provider may recommend additional folic acid supplements over the amount in a prenatal vitamin.

Can Prenatal Vitamins Cause Side Effects?

Sometimes, the iron in prenatal vitamins causes constipation. The best way to prevent or manage constipation is to drink at least eight glasses of water daily and eat more fiber. Good sources of fiber include:

  • All fruits and vegetables.
  • Whole grains like oatmeal, barley, or brown rice.
  • Legumes (beans).
  • Nuts and seeds.
  • Dried fruit like apricots, raising, or prunes (or prune juice).

If adding more fiber foods doesn’t help, you can ask your doctor about taking a fiber supplement or using a stool softener. These may make bowel movements softer, bulkier, and easier to pass.

You can also try a prenatal vitamin that contains a different form of iron. Sometimes one form will make you constipated, but another may not.

Prenatal vitamins are often large, and some people have trouble swallowing them. Or they may feel nauseous when taking them. If that’s the case, ask your doctor or pharmacist if you can cut the pill in half or if there is a smaller option.

Sometimes, prenatal vitamins can increase nausea, especially in the first trimester. Many pregnant patients prefer to take gummy prenatal vitamins in the first trimester. Gummy vitamins generally contain most of the nutrients listed above, with the exception of iron. It is recommended to switch to a prenatal vitamin with iron in it once you are in the second trimester.

If you’re looking for a good prenatal vitamin, it’s always wise to check with your obstetrician. They can recommend the best one with all the nutrients you need based on your diet. And keep in mind, if you’re carrying more than one baby, they may recommend that you take higher amounts of certain nutrients.

Nutrients. Nutrient Requirements during Pregnancy and Lactation. LINK.

March of Dimes. Vitamins and Other Nutrients During Pregnancy. LINK

U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. LINK

About UPMC Magee-Womens

Built upon our flagship, UPMC Magee-Womens Hospital in Pittsburgh, and its century-plus history of providing high-quality medical care for people at all stages of life, UPMC Magee-Womens is nationally renowned for its outstanding care for women and their families.

Our Magee-Womens network – from women’s imaging centers and specialty care to outpatient and hospital-based services – provides care throughout Pennsylvania, so the help you need is always close to home. More than 25,000 babies are born at our network hospitals each year, with 10,000 of those babies born at UPMC Magee in Pittsburgh, home to one of the largest NICUs in the country. The Department of Health and Human Services recognizes Magee in Pittsburgh as a National Center of Excellence in Women’s Health; U.S. News & World Report ranks Magee nationally in gynecology. The Magee-Womens Research Institute was the first and is the largest research institute in the U.S. devoted exclusively to women’s health and reproductive biology, with locations in Pittsburgh and Erie.