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7 Prenatal Side Effects That You Need To Be Aware Of

7 Prenatal Side Effects That You Need To Be Aware Of

Pregnancy is an experience like no other, but sometimes, taking prenatal vitamins can cause a few hiccups.

From bouts of nausea to the occasional feeling of being "backed up," these prenatal vitamin side effects are minor and temporary, and they pose no significant threat to you or your baby.

In this article, we talk about the seven most common side effects of prenatal vitamins and share some simple tips on how you can manage them for a smooth-sailing pregnancy.

7 Common Prenatal Vitamin Side Effects


Iron is an important nutrient you need for a healthy pregnancy.

It helps the body produce hemoglobin, a part of red blood cells that delivers oxygen to support your baby’s growth and development.

It can also support a full term pregnancy, as it helps prevent anemia related to iron deficiency.(1)

However, according to a study by The Cureus Journal, iron can pull water away from the GI tract, which can result in constipation and GI cramping.(2,3,4)

Similarly, other trace minerals such as calcium and zinc can also make it hard for you to urinate.

Calcium contracts the muscles of the GI tract, slowing stool transit and resulting in constipation.

Meanwhile, taking too much zinc can interfere with the absorption of nutrients that are important for maintaining bowel regularity, such as copper and iron.(5)

Not only that, but taking prenatal vitamins in tablet form can also be difficult to digest, making stools hard to pass.

To help make your bowels move easier, taking prenatal vitamins in powder, chewable, or capsule form is a great option.

You can also use prenatal vitamins with chelated minerals in them, as they are more digestible and absorbable than non-chelated minerals.

Also, make sure to stay well hydrated and eat foods rich in fiber to help with normal bowel movement.

Sleep Issues

Prenatal vitamins, especially ones that don’t contain much folate, choline, or B12, can make it hard for you to fall asleep.

This is because low folate levels can lead to sleep disturbances, decreased sleep efficiency, and impaired sleep continuity according to a study from the University of Pennsylvania.(6)

This occurs for two reasons.

First, low folate may interfere with your circadian rhythm or so-called biological clock, making it difficult for you to sleep at night even if you want to.(7)

Second, a deficiency in folate levels can lead to neurotransmitter imbalance, resulting in sleep difficulties.

You see, folate plays a role in synthesizing neurotransmitters, such as melatonin and serotonin. Both of them are important in regulating sleep-wake cycles.(8) 

Specifically, folate is important in 5-hydroxytryptophan (5-HTP) synthesis, a precursor of serotonin.(9)

Serotonin is also the precursor of the hormone melatonin, which is responsible for regulating sleep.(10)

A deficiency in folate can lead to a melatonin and serotonin imbalance, causing sleep issues in pregnant women.

Moreover, low levels of choline can also influence your sleep quality, making it difficult to fall asleep and stay asleep at night.(11)

To help you get your well-deserved sleep every night, make sure to take your prenatal vitamin six hours before bedtime.

As much as possible, take it with meals to minimize the side effects of pregnancy vitamins.


Prenatal vitamins can cause headaches if they’re not suitable for you.

For example, some women can’t tolerate folic acid, a synthetic form of vitamin B, causing headaches.

Therefore, it’s advisable to use either methylfolate or folinic acid, which are naturally occurring forms of folate commonly found in foods.

They are easier to absorb and gentler on the digestive system, reducing your chances of experiencing prenatal vitamin side effects like headaches.

Similarly, methylcobalamin, a form of B12, can also be too stimulating when used.

In this case, use hydroxocobalamin as your form of B12 instead, which can be naturally converted by the body into methylcobalamin for the cells to absorb and use.

Taking excess amounts of prenatal vitamins can also make your head hurt.(12)

You can talk to your doctor about reducing the frequency and amount of prenatals you are taking.

Remember: prenatal vitamins can help support a healthy pregnancy journey.

However, you should still get the majority of your daily nutrients from foods, although industrialized farming techniques and depleted soils can make this impossible for many.

That’s where prenatals come in.

If you are eating well, you may not need the full serving size of your prenatal vitamin.

Irritability or Anger Outbursts

Taking high doses of prenatal vitamins may cause women to experience mood changes or unease.

This is often caused by the high levels of iron in the supplement.

In a study published by Frontiers of Aging Neuroscience, high iron levels can affect brain function in women, resulting in mood swings and irritability.(13)

Similarly, a lack of iron can minimize oxygenation in your body, making it hard to focus and potentially causing anger outbursts.

Similarly, low levels of vitamin B12 may lead to unease and mood swings.

Vitamin B12 helps in neurotransmitter production like dopamine and serotonin, which are critical for mood management.

Therefore, supplementing with healthy amounts of iron and B12 can help support a healthy mood and feelings of calm.(14) 


If you do not take enough folate, your body can’t produce enough red blood cells that deliver oxygen throughout your body.

This may lead to folate deficiency anemia, resulting in fatigue and tiredness.

Fortunately, taking healthy amounts of folate may help maintain healthy levels of red blood cells in the body, supporting healthy energy.(15)

If you’re still experiencing fatigue despite taking the right dosage consistently, it may be because you are using a poor-quality prenatal.

You see, a good prenatal vitamin should support healthy energy levels.

In this case, switch to a prenatal that has high-quality ingredients, just as with Seeking Health’s prenatal supplements.

You can also opt for calcium foliate (folinic acid) instead of methylfolate, as the latter can make you feel more tired.

This is because of the active detoxification that’s been started by methylfolate at a faster rate than the body can adapt.

Nausea and Vomiting

Nausea and vomiting are common events in pregnancy.

To avoid vomiting and nausea caused by prenatal vitamins, always take your prenatal with a meal, not just a snack or bite of food.

Vitamins that use chelated minerals are also a great option.

Chelated minerals like ferrous bisglycinate chelate bind to amino acids so that they can pass into the cells more easily, meaning they cause fewer side effects, including nausea.(16)

Apart from that, you can support occasional intermittent nausea and vomiting related to pregnancy by using Histamine Digest.

Nausea and vomiting during pregnancy are often caused by high levels of histamine.

By supplementing with Histamine Digest, ProBiota HistaminX, and/or Histamine Nutrients, which all are safe for pregnant women, you are supporting healthy histamine levels during pregnancy.

Skin Irritation

Vitamin A is an important nutrient for fetal growth and development.

However, taking more than the desired amount can cause skin irritation, including dry and itchy skin.(17)

It’s also very important to note that taking 10,000 micrograms or more of vitamin A per day may cause birth defects in your baby.

If you’re agonizing over itchy skin, raise this concern with your doctor immediately so they can adjust your dose, allowing you to still maximize vitamin A’s benefits while minimizing the prenatal vitamin’s side effects.

Changes in Urine Color

Notice bright yellow pee in early pregnancy?

That is another side effect of taking prenatals, especially B vitamins.

B vitamins are water-soluble and can be excreted in your urine.

For example, take vitamin B2 or riboflavin.(18)

This nutrient has a yellow-green pigment with fluorescent hues. When mixed with urine, it can turn your pee bright yellow.

However, don’t worry! Bright yellow urine in pregnancy is harmless.

Drinking more water can help solve the issue, but you should talk with your doctor if you have any concerns.


When taking prenatal vitamins, make sure you take the recommended dose, as overnutrition can pose a serious threat to you and your baby’s health.

Always consult with your doctor before taking anything and follow up with them if you experience unusual side effects.

It’s also best to choose high-quality prenatal vitamins to support your journey throughout pregnancy.

You can find some of the best prenatal vitamins and supplements at Seeking Health.

We create our products with mommies and babies in mind – it’s no wonder they love us!

That’s not to mention we offer pure and safe vitamin content, and all our products are third-party tested, making sure that what you get and give your baby is healthy for them.

Are you ready? Shop now!



‡ These statements have not been evaluated by the Food and Drug Administration (FDA). This product is not intended to diagnose, treat, cure, or prevent any disease.

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