What Are Prenatal Vitamins and Why Are They Important?

Prenatal vitamins play the role of supplementing the natural diet of a pregnant woman. Their function is to compensate for some specific gestational requirements.
What Are Prenatal Vitamins and Why Are They Important?
Leidy Mora Molina

Reviewed and approved by the nurse Leidy Mora Molina.

Written by Edith Sánchez

Last update: 15 December, 2022

Prenatal vitamins are a great option to supplement your diet during pregnancy. Many mothers have questions about this though, because there are a lot of myths and misinformation circulating.

It’s clear that a healthy diet is the best way to get all the nutrients needed for pregnancy. The point is that, during pregnancy, some key nutritional elements are required in greater quantities.

Because of this, it’s highly recommended to take prenatal vitamins before getting pregnant. Which are the best ones? Are they risky? We’ll talk about all this below.

What are prenatal vitamins?

Prenatal vitamins are food supplements that help to obtain the necessary nutrients to ensure the baby develops normally. What they do is supplement a proper diet. They provide the daily vitamins and minerals required during pregnancy.

It’s possible that the usual diet may fall short in the supply of crucial nutrients for the healthy growth of the baby. These supplements are more important in women who have some health problems or dietary limitations, as in the following cases:

  • Vegetarian or vegan mothers
  • Lactose intolerance or intolerance to other foods
  • Tobacco or drug use
  • Eating disorders
  • Circulatory system problems
  • Previous gastric bypass
  • Pregnancy with more than one baby

The importance of prenatal vitamins

During pregnancy, there’s an increased requirement for nutrients such as folic acid, calcium, iron, and omega-3 fatty acids. Prenatal vitamins help ensure that you’re getting all of these elements in the right proportions.

The two main elements are folic acid and iron. However, ideally, a prenatal vitamin supplement should contain some additional ones.

Foods with folic acid or vitamin B9 need to be in the mother’s diet, but it’s good to boost with a supplement.

Folic acid

It’s estimated that taking an adequate amount of folic acid during the month before conception and at the beginning of gestation reduces the risk of the baby having a neural tube defect, such as anencephaly or spina bifida, by up to 70%.

This substance also reduces the risk of other birth defects, such as cleft lip and palate and some heart problems. It even decreases the chance of pre-eclampsia.

The synthetic version of folic acid is better absorbed by the body than the one that comes in natural foods. Most prenatal vitamins contain this element and it’s essential to make sure this is the case with the one we consume and are prescribed.


Pregnancy requires a very high intake of iron. It’s difficult to obtain it in sufficient quantity from the normal diet.

Prenatal vitamins help to compensate for this deficiency and to prevent the risk of anemia. This pathology increases the risk of premature birth and low birth weight.

You might also be interested in: Infusions for Anemia


Prenatal vitamins don’t always contain calcium or include it in low quantities. That’s why it’s very important to obtain it also from natural sources. This element contributes to the healthy development of bones, teeth, nerves and muscles, including the heart.

Essential fatty acids

Only some prenatal vitamins contain essential fatty acids. These include omega-3, DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid).

All three contribute to the development of the baby’s brain, nervous system and eye tissue. Ideally, they should be obtained from natural foods and supplements.

Vitamin D

Vitamin D is essential for maintaining balanced calcium and phosphorus levels in both mother and baby. Deficiency of this nutrient increases the risk of rickets, abnormal bone development and some delays in physical development.

It’s suspected that this deficiency also contributes to preeclampsia and gestational diabetes. It’s important, therefore, that prenatal vitamins contain this element.

When to take prenatal vitamins?

Ideally, the mother should start taking folic acid before becoming pregnant. This is because the baby’s neural tube develops during the first month of gestation. This tube develops into the baby’s brain and spinal cord.

However, many women don’t even know they’re pregnant until after the first month. The important thing, then, is that as soon as they find out, they start taking prenatal vitamins.

It would be ideal for a woman to start taking these vitamins whenever she’s looking to become pregnant.

Are there any side effects?

Most women tolerate prenatal vitamins well and have no difficulty taking them. However, some report nausea. This occurs when more than 30 milligrams of iron are taken. A higher amount of the mineral irritates the digestive tract.

It would be best to take prenatal vitamins with food or before bedtime. If the problem persists, consult your doctor to recommend another supplement.

There are also a percentage of women who experience constipation as a side effect. Again, this is the fault of the iron. The best thing to do is to take a supplement with a lower proportion of the nutrient and maintain a diet with plenty of fiber, water and fresh foods.

Pregnancy supplement.
The best prenatal vitamins will be recommended by the obstetrician. This will be based on each mother’s medical situation.

Tips and recommendations when taking prenatal vitamins

The physician will be the one to indicate which prenatal vitamins are most appropriate for each individual woman. Many people will want to give their opinion, but it’s the professional who is qualified to establish what is safest.

Some prenatal vitamins contain herbal ingredients. It isn’t advisable to use these products, as there’s no research to support their efficacy or to fully certify the risks of these components.

Generally speaking, almost all mothers should take a minimum daily intake of the following components:

  • Folic acid: 400 micrograms
  • Iron: 27 milligrams
  • Calcium: 1000 milligrams
  • Vitamin D: 200 to 600 international units

It isn’t advisable to take another nutritional supplement while taking prenatal vitamins. Unless told to do so by the doctor.

These combinations could bring problems.

It’s necessary to emphasize that prenatal vitamins are a complement to the natural diet and not a substitute. The mother should follow her doctor’s nutritional advice and eat very well, in a natural way, to successfully carry out the pregnancy.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Lindemann, O. (2000). Medicación y suplementos en el embarazo: ¿Son necesarios como tratamiento rutinario? Natura Medicatrix: Revista médica para el estudio y difusión de las medicinas alternativas, (61), 28-30.
  • Quevedo C, L., Rojas, M., & Soto, M. (2011). Intolerancia a la lactosa. Rev. pediatr. electrón.
  • America, S. (2017). ¿Qué debe tener en cuenta a la hora de elegir sus vitaminas prenatales? Tori Schmitt, MS, RDN, LD. Compartir.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.