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Prenatal vitamins make me sick

Can Prenatal Vitamins Make You Sick?

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Many women find prenatal vitamins hard to stomach, and I often have patients ask me if they have to take them. The short answer is, it depends.

The necessity of taking prenatal vitamins depends on your nutritional status at the beginning of pregnancy. Are you well nourished, malnourished or obese? In the U.S., if you are eating a normal healthy diet, vitamin and mineral supplements are probably not required. When there is a problem with inadequate sources of vitamins or minerals, the first solution is a healthy diet.

If you are planning to become pregnant, it is a great idea to schedule a pre-pregnancy visit with your obstetrician who will make sure that you are up to date with all vaccinations and check your blood count and iron level. If you meet certain criteria, it may also be advisable to check your glucose levels and your levels of vitamin D. By meeting with your doctor prior to conception, you will know your nutritional status and can start to make any necessary dietary adjustments to prepare for pregnancy.

Once you become pregnant, a prenatal vitamin can be a very important part of your healthcare routine. The two most important ingredients of the prenatal vitamin are folic acid and iron. Below I will explain what each of these vitamins is, why it’s important, and the suggested daily intake for expecting mothers.

Folic Acid

Some physicians advocate for preconception folate supplementation as a way to reduce birth defects and improve pregnancy outcome. Women who are planning to become pregnant should consider taking a multi-vitamin with at least 400 µg of folic acid daily for at least a month prior to conception. There are certain instances, such as a prior pregnancy with spina bifida, where 4000 µg (or 4 mg daily) is advised.

Since we know that nausea is very common in the first three months of pregnancy, make sure that your body is well supplied with both macro- and micronutrients prior to conception. This will help you to weather any temporary reductions in your food supplies.

Studies have shown that women who take a prenatal vitamin prior to conception have less nausea during pregnancy. If you are unable to take your prenatal vitamin in the first trimester due to nausea, your obstetrician may recommend that you switch to a folic acid supplement until your nausea improves.


Since you are building the blood volume of the fetus, you will need to provide about 1000 mg of iron to the fetal-placental unit over the 40 weeks of pregnancy. Much of this can be achieved with the correct diet, however, taking 30 mg of iron daily can be of great assistance.

For some people, iron causes significant GI issues such as nausea or constipation. If your blood count is low, I would encourage you to take the additional iron, drink plenty of fluids and use stool softeners to help decrease unwanted side effects. Some prenatal vitamins don’t contain iron, and you can take one of these until your nausea improves.

Other Crucial Vitamins

In addition to the folic acid and iron, it takes about 30 grams of calcium to build the fetal skeleton and most of this growth occurs during the last 10 weeks. Your diet and prenatal vitamin will certainly provide adequate reserves. Most women do get heartburn during their pregnancy. It is perfectly okay to use Tums or Rolaids and these antacids are loaded with calcium.

The U.S. Department of Agriculture’s website has great suggestions for food sources that have the needed vitamins, and features an interactive diet-planning program specifically for women who are pregnant or breastfeeding.

Having a baby? Our team has answers to your questions and more. Find an Ochsner OB-GYN today.

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