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Prenatal Vitamins Can Trigger Nausea. Here Are 11 Ways to Mitigate It.


Up to 85% of pregnant women experience nausea in the first trimester, especially between weeks 6 and 15 or so. While this is very common and doesn’t harm the pregnancy in a vast majority of cases, we know it can still be a struggle, physically, psychologically, socially and sometimes economically.

Nausea can also make it hard for some women to take or keep down prenatal vitamins, which are designed to support the mom and the baby during this crucial time through optimal nutrition. 

The good news is that there are strategies to help mitigate the worst of nausea and vomiting during pregnancy for most women – and it actually starts before you are pregnant. Let’s start with the physiology, and we’ll share our 11 tips to keep taking your prenatals during this rough part of your pregnancy.


What causes nausea during pregnancy?

Studies have pointed to several hormones as potential causes of nausea in pregnancy, including human cholionic gonadotropin (hCG), a “pregnancy hormone” excreted by the placenta, as well as estrogen. Women tend to have worse symptoms of nausea and vomiting when the levels of these hormones are higher.


Prenatal vitamins themselves can contribute to nausea

Prenatal vitamins themselves can, unfortunately, worsen nausea in several ways. The three most common prenatal ingredients that can worsen nausea are iron, iodine and choline.


1. Iron: Gut bacteria imbalance

Iron (and to a lesser extent, other minerals) in prenatal vitamins can cause nausea, constipation and other GI issues. Scientists think that this is because iron and other minerals can be hard to absorb and can accumulate in the digestive tract, which may affect the balance of the gut microbiome.

A healthy level of iron is important during pregnancy because it’s a necessary element to produce the extra blood for you and the baby, but more iron in prenatal vitamins isn’t better. American College of Obstetricians and Gynecologists recommends 27 mg/day for pregnant women. If you have a healthy level of iron in your body and get enough iron from diet, switching to a brand of prenatal vitamins without iron can also be an option. Talk to your doctor.

Recently, chelated amino acid minerals have been suggested as a possible workaround. Chelated minerals like ferrous bisglylcinate chelate (one type of chelated iron) are minerals bound to amino acids, designed to make them pass into the cells more easily. Although the evidence isn’t conclusive, some studies have suggested that chelated iron and other minerals may cause fewer and less severe side effects, including nausea. Prenatal vitamins that use chelated minerals may be a good option for you if you find iron and other minerals in their typical non-chelated forms hard on your stomach.



2. Iodine: Active thyroid glands

Your thyroid glands need iodine to produce enough thyroid hormones for both you and the baby. A healthy iodine level also supports the baby’s brain development and normal cognitive functions. Some of the necessary iodine comes from your diet (seaweed is an excellent source of iodine), and your prenatal vitamins should have enough to close any gap.

Human chorionic gonadotropin (hCG) also stimulates the thyroid glands. More active thyroid has been known to worsen nausea during pregnancy. Combined with hCG’s action on the thyroid glands, too much iodine can aggravate nausea. This is why the World Health Organization and other professional organizations recommend 150 mcg of iodine in prenatal vitamins as a good balance. If your prenatal vitamins contain far more than this amount, you may consider switching to another prenatal with less iodine.


3. Choline: Sulfuric smell

Choline is a key nutrient in the early pregnancy that a vast majority of women are not getting enough of. Just like folate, choline supports the baby’s healthy brain development, and as such, helps prevent neural tube defects. However, it can also contribute to nausea. It’s not because of how it’s absorbed or how it works in the body, but rather because choline has a slightly sulfuric smell that can be off-putting for some women.


11 strategies to mitigate nausea to stay on your prenatal vitamins

Aside from finding a prenatal vitamin brand that works for you, there are some things you can try to reduce nausea from prenatal vitamins and in general – both for your prenatal health and for your quality of life. 

  1. Start early. Some studies (like this one) have suggested that getting started on prenatal vitamins before pregnancy might help reduce the likelihood and severity of nausea once pregnant. The reason is unclear, but one theory is that women who are well nourished when conception happens – especially with Vitamin B6 (see below) may be able to better withstand the hormonal changes that can cause nausea. So, if you are trying, get started on the prenatal vitamins now, rather than wait until you are pregnant.
  2. Ease into it. Especially if your prenatals cover a lot of nutritional ground, both in terms of the number of nutrients and in terms of their doses, starting with a portion of the daily dose and gradually increasing your dose may help your digestive system get used to the prenatals.
  3. Try increasing your Vitamin B6 intake. Several randomized controlled trials have suggested that Vitamin B6 helps improve symptoms of nausea and vomiting during pregnancy. Make sure your prenatal vitamins have an adequate amount of B6 – especially if you’ve been on hormonal birth control, which can deplete the body of this B vitamin.
  4. Eat first, prenatals second. Taking your prenatals with some food – even something as small as a few crackers or some smoothie – can help with nausea.
  5. Drink plenty of water. Your water needs increase when you are pregnant, and dehydration can set in more quickly, which can make nausea worse. Try to drink 8 to 12 cups of water a day to stay hydrated.
  6. Spread out your dose. If your prenatals consist of multiple capsules (and they should), spreading out the daily dose over 2 or 3 meals can also help you keep them down.
  7. Let them air out. Taking your prenatals out of their packaging and letting them air out reduces the typical prenatal vitamins smell. A few hours to a day in the open won’t degrade the ingredients, either, so go ahead and let the smell dissipate.
  8. Try changing your timing. Women experience “morning sickness” differently - it's not always the worst in the morning. See if you have a daily pattern, and schedule your prenatals for when you tend to feel your best.
  9. Aim for stable blood sugar levels. One oft-overlooked cause of nausea is the fluctuation in blood sugar levels. Women who don’t have a problem normally can find stable blood sugars a challenge during pregnancy. Try to keep your blood sugar levels stable with healthy fats (nuts, for example, if you can stomach them), whole grains (like whole grain crackers) and protein (yogurt can work for some women), and see if that improves your symptoms.
  10. Share your struggles. Multiple studies have shown that psychological and social factors make this challenging time more or less bearable, even when the symptoms are similar. Share with your support system what you are going through, and lean on them for help.
  11. Talk to your doctor. Many women suffer through it because it’s so common, but your doctor can suggest lifestyle and dietary modifications to help you regain your quality of life. There are also safe medications to alleviate the symptoms. Doctors recommend early treatment, because early treatment is more effective and makes the first trimester easier on you and the baby.

Last but not least: If your nausea is so severe you can’t keep anything down and start losing weight, it’s definitely time to talk to your doctor. It’s relatively rare, but some women are affected by what’s called hyperemesis gravidarum, and need medical treatment to maintain the health of the mom and the baby.

Please reach out if any other questions come up around managing nausea and sticking to your prenatal vitamins. We are with you.



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