Vitamin K2 While Pregnant: Benefits, Risks, and Sources

author avatar Dr. Eric Berg 10/26/2023

Maintaining optimal levels of vitamin K2 while pregnant supports fetal bone development, prevents neonatal hemorrhagic disease, and helps lower the risk of complications during childbirth.  

Discover the benefits of vitamin K2 for pregnant and lactating women and know the signs and symptoms of vitamin K deficiency.   

Pregnant woman

What is vitamin K2?

Vitamin K belongs to the group of fat-soluble vitamins and naturally occurs in two main forms: vitamin K1 and vitamin K2.

While vitamin K1 is predominantly found in plant foods, vitamin K2 can be obtained from certain animal products and fermented foods and is generally considered the more effective form of vitamin K. 

Vitamins K1 and K2 regulate the production and activation of blood clotting proteins, also known as coagulation factors, which are critical for wound healing and preventing excessive bleeding.

In addition to its role in blood clotting, vitamin K2 is crucial for calcium balance and redirects calcium from the blood into bones and teeth. This supports bone metabolism and lowers the risk of calcium accumulation in soft tissues such as blood vessels, joints, and tendons.

Maintaining a healthy vitamin K status is vital for human health, and deficiency can significantly increase the risk of brittle bones, osteoporosis, and vascular calcification, a primary risk factor for heart disease. 

Watch the video below to learn how nutrient deficiencies can impact fetal growth and development. 

Is it safe to take vitamin K2 while pregnant?

Taking vitamin K2 is considered safe during pregnancy, and most prenatal supplements contain vitamin K.

Research published in the Cochrane Library suggests that vitamin K2 supplementation plays an important role in lowering the risk of vitamin K deficiency bleeding (VKDB), a rare but potentially serious neonatal bleeding disorder caused by inadequate vitamin K levels at birth.  

In addition, a study published in Children found that “The lack of adverse or toxic effects of vitamin K2 makes it the ideal choice for supplementation by pregnant and nursing women.”

Vitamin K capsule

Three benefits of vitamin K2 during pregnancy

Vitamin K2 is a critical factor for calcium balance, skeletal health, and blood clotting, which are crucial aspects of fetal development and maternal health.

Here are three benefits of vitamin K2 during pregnancy.

1. Promotes skeletal health   

Vitamin K2 activates matrix Gla proteins (MGPs), a group of proteins that bind to calcium and facilitate its deposition into bone and teeth. 

Without adequate vitamin K2, dietary and supplemental calcium can’t effectively be incorporated into bone tissue, which can impair skeletal development, bone health, and fetal growth. 

2. Supports brain development 

Vitamin K2 regulates calcium balance and plays an important role in fetal brain development. 

Maintaining healthy maternal blood calcium levels is vital for the central nervous system, including neurotransmitter release, neuronal signaling, and synaptic plasticity, all fundamental aspects of the baby's brain development and function.

3. Lowers the risk of complications during childbirth 

Vitamin K2 is essential for the production and activation of blood clotting factors, which is crucial to prevent postpartum hemorrhage, a potentially serious condition characterized by excessive bleeding during or after childbirth. 

Woman with a bruise

Vitamin K2 deficiency: signs and risks

Pregnancy and lactation is a critical period of heightened energy and nutrient needs to support fetal growth and breast milk production, leaving pregnant and breastfeeding mothers at risk of nutritional deficiencies, including vitamin K.

Here are common symptoms of vitamin K deficiency:

  • Excessive bleeding

  • Easy bruising

  • Bleeding gums

  • Blood in stool or urine 

  • Heavy menstrual flow 

Inadequate vitamin K status can have adverse effects on fetal development, including insufficient bone mineralization, and has been linked to an increased risk of VKDB. 

In addition, vitamin K deficiency can contribute to postpartum hemorrhage and may cause arterial calcification, a leading risk factor for atherosclerosis, heart attacks, and stroke. 

Fermented foods

Natural sources of vitamin K2

A study published in Environmental Health and Preventive Medicine reports that fermented foods such as natto, sauerkraut, tempeh, and kefir are some of the top vitamin K2 food sources

In addition, egg yolks, oily fish, beef liver, chicken, butter, and cheeses such as gouda, camembert, and edam also contain vitamin K2, and regularly consuming these food sources can support healthy vitamin K levels.  

Vitamin K1, which is predominantly found in plant foods, including green vegetables, can be converted into vitamin K2 by certain gut bacteria. 

“It’s important to note that the efficiency of this conversion process varies greatly,” explains Dr. Berg. “And relying only on microbial vitamin K2 production to maintain adequate vitamin K status can lead to deficiency.”  

Pregnant woman taking supplements

How much vitamin K2 can you take during pregnancy?

Most health professionals suggest a daily intake of 90 mcg of vitamin K2 during pregnancy and breastfeeding. 

However, individuals with Crohn’s disease or inflammatory bowel disease (IBD) and those taking anti-seizure medication may require larger vitamin K2 doses and should consult a healthcare provider for guidance on appropriate vitamin K intake during pregnancy.  

In addition, vitamin K2 works in synergy with vitamin D3 to maintain calcium balance and bone health, and it's crucial to take a prenatal supplement that contains both of these fat-soluble vitamins. 

Lack of adequate vitamin D during pregnancy can impair fetal bone development and increase the risk of poor immunity during infancy. 

The best ratio of vitamin D3 and K2 is around 1000:10, meaning you should choose a prenatal supplement that contains around 10 mcg of vitamin K2 for each 1000 IU of vitamin D and at least 400 mcg of folic acid to support healthy neural development.  

Pregnant woman and little girl

Key takeaways

Vitamin K2 is an essential vitamin that regulates calcium balance and blood clotting, supports strong bones, and lowers the risk of arterial calcification and bleeding disorders. 

Taking vitamin K2 while pregnant is a safe and effective strategy to promote healthy fetal development and skeletal health, and lowers the risk of excessive bleeding during childbirth.

Additional vitamin K2 and D3 resources


1. Can you take vitamin D3 and vitamin K2 while pregnant?

Vitamin D3 and K2 are safe and well-tolerated during pregnancy if taken in recommended dosages.  

These two fat-soluble vitamins work in synergy to regulate calcium balance and bone mineralization, which is crucial for maternal health and fetal development. 

2. Who should not take vitamin K2?

Individuals with blood clotting disorders, kidney disease, or poor liver health and those taking blood thinning medication or anti-seizure drugs should consult a healthcare professional before taking vitamin K2 supplements to minimize the risk of side effects. 

3. Does vitamin K2 cross the placenta?

Although vitamin K2 has been found to cross the placenta, it’s thought that only small amounts of vitamin K can enter the fetal circulation. This explains why infants are at increased risk of vitamin K deficiency and typically receive vitamin K2 supplementation immediately after birth.   


4. Do prenatals have K2?

While prenatal supplements often contain vitamin K, most brands contain vitamin K1, which supports blood clotting but has minimal benefits for calcium balance and bone health. In contrast, vitamin K2 regulates skeletal calcium deposition and promotes fetal bone development.  

If you believe you would benefit from taking vitamin K2 during pregnancy, consult a healthcare provider to identify an appropriate prenatal supplement. 

5. Is vitamin K2 safe during pregnancy?

Yes, vitamin K2 is considered safe during pregnancy and has not been found to cause adverse health effects or toxicity when taken in recommended dosages. 


6. Why is vitamin K2 important in pregnancy?

Vitamin K2 is a fat-soluble vitamin that plays an important role in blood clotting, which lowers the risk of neonatal bleeding, also known as hemorrhagic disease.

In addition, vitamin K2 regulates the deposition of calcium into bone and teeth, supporting skeletal development and strong bones. 

7. How much vitamin K2 should I take while pregnant?

It’s recommended that pregnant women take 90 mcg of vitamin K2 daily to maintain healthy vitamin K status and prevent deficiency. 

8. What are the risks of taking too much vitamin K2 during pregnancy?

Taking too much vitamin K2 during pregnancy can lead to abnormal blood clotting and increase the risk of thrombosis in both the mother and the developing child. 

In addition, excessive amounts of vitamin K2 can lead to gastrointestinal symptoms, including nausea, vomiting, and diarrhea, and may increase the risk of kidney and liver damage. 

9. What are the best natural sources of vitamin K2 for pregnant women?

Some of the best natural vitamin K2 sources include egg yolks, oily fish, butter, cheese, organ meats, and fermented foods such as sauerkraut, kimchi, kefir, and natto, a Japanese soybean dish. 





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