Vitamin K1 and K2 During Pregnancy

Vitamin K plays a few important roles during pregnancy. It supports bone health, aids in blood clotting, and helps ensure both you and your baby have a healthy microbiome, but vitamin K1 and vitamin K2 have slightly different roles in the body.

Vitamin K1

Vitamin K1 (phylloquinone) tells your body to stop bleeding, which is crucial during childbirth. This vitamin also plays a vital role in bone health, wound healing, and is the type given to babies after birth, either orally or by injection, to prevent Vitamin K Deficiency Bleeding (VDKB.)

Foods High in Vitamin K1

Vitamin K1 is found in large quantities in leafy green vegetables such as spinach, kale, Brussels sprouts, and broccoli, as well as in certain fruits, making it relatively easy to consume in significant amounts. Most healthy adults eating a balanced diet that include leafy green vegetables are not deficient in vitamin K1. Still, many prenatal vitamins include Vitamin K1 because it is highly absorbable and is vital for blood clotting.

Vitamin K2

Vitamin K2 (menaquinones) primarily tells your body what to do with calcium. When Vitamin K2 levels are adequate, calcium goes into your bones and teeth where it belongs. Like its cousin K1, it also helps your blood to clot, but K1 is more dominant under these conditions.

Vitamin K2 Family

To make matters more complicated, vitamin K-2 comes comes from a big family called menaquinones  (MK), which range from MK-4 to MK-13. Out of all the MKs, MK-4 and MK-7 are the main players in pregnancy, but it is MK-7, along with vitamin K1 that you will find in prenatal vitamins..

Functions of MK-4 and MK-7

While MK-4 and MK-7 are both essential for good bone health, they are distributed differently in the body.

• The primary function of Vitamin K2 (MK-7) is to direct calcium to the bones.

• MK-4 is also found in the bones, but it rapidly delivered to other parts of the body, such as the pancreas and reproductive organs. It is well known for its ability to support normal brain function (Schurgers).

• The placenta contains both phylloquinone (K1) and various menaquinones (K2), but MK-4 is present at higher concentrations. However, very little vitamin K crosses the placenta into the fetal blood, which is why newborns are typically vitamin K-deficient at birth.

  
  

Vitamin K2 Food Sources

K2 MK-7 Food Sources

MK7 is produced by bacteria found in fermented food. Natto is the highest form, but it is also found in some fermented cheeses and sauerkraut.

K2 MK-4 Food Sources

MK-4 primarily comes from grass-fed and free-range animal products, such as meat, liver, and fermented dairy products like yogurt and certain cheeses, such as Brie, Camembert, or Gouda. Egg yolks are another good source of MK4. Grass-fed animals synthesize vitamin K2 from the vitamin K1 they obtain from the grass. In contrast, animals on a grain diet have limited access to vitamin K1 because it's found almost exclusively in green plants. If you are a vegetarian, your primary dietary source of vitamin K2 is Natto.

Conversion

Your body has an amazing ability to convert leafy greens (which contain vitamin K1) into MK-4. It is also possible that MK-7 is converted, but the conversion is complex. Ultimately, eating a diet rich in both vitamin K1 and K2 (MK-7 and MK-4) ensures adequate levels of vitamin K forms essential to pregnancy and breastfeeding.

highlighting the importance of including different forms of vitamin K in your diet to maintain adequate levels of MK-4.

Which MK Should I Take? 

Studies have found that vitamin K2 deficiency is prevalent among women in the later weeks of pregnancy (Liu, 2025; Lippi and Franchini, 2011), underscoring the importance of regularly consuming vitamin K2-rich foods or taking supplements.

Both MK4 and MK7 are valuable during pregnancy, but you are most likely to see MK7 in prenatal vitamins. That's because MK-4 is difficult to add to vitamins, primarily because of its short half-life, which affects how it is used and dosed. A short half-life, however, does not translate into an inferior product. The half-life means it is quickly removed from the body, but it does not matter how long something lasts in the body; it is the health benefits you need to consider.

How Much Vitamin K?

While there is a recommended daily intake for vitamin K 1, there is none for vitamin K2, likely due to the wide range of vitamin K forms. It has been suggested that the mean intake of vitamin K ranges from 70 µg/day to 300 µg/day (Mladěnka).

Vitamin K1 Supplemental Intake

According to the National Institutes of HealthTrusted Source, adequate intake for vitamin K1 is 90 mcg.

Vitamin K2 (MK-7) Supplemental Intake

While there is no specific recommended intake for vitamin K2 (MK-7) during pregnancy, general guidance suggests up to 90 micrograms a day for pregnant women.

Vitamin K2 (MK-4) Supplemental Intake

The MK-4 found in food is a natural, absorbable form that the body can use efficiently, making good dietary intake the best choice. It's swift metabolism means it won't linger longer, necessitating a consistent intake of foods from grass-fed sources, like egg, organ meats (liver), muscle meats, dairy, and fermented cheeses to maintain its potential beneficial effects. If you feel you do not get enough dietary sources of vitamin K2 MK-4, or vitamin K2 MK-7 for that matter, you may consider taking a supplement.

Check out My Favorite Supplements to find high quality prenatal vitamins. Most have one or both forms of vitamin K (K1 and 2). If not, look for a dedicated MK-7 or MK-4 supplement to meet your nutritional needs. Always consult your provider before adding new supplements during pregnancy.

Diet and Lifestyle Overview

• Eat vitamin K1-rich foods, such as kale, Swiss chard, broccoli, and Brussels sprouts.

• Consume vitamin K2 (MK-7) foods such as natto, sauerkraut, and kefir.

• Eat vitamin K2 (MK-4) rich foods from grass-fed sources, like egg, organ meats (liver), muscle meats, dairy, and fermented cheeses.

• Vitamin K is fat-soluble and requires dietary fats for absorption, so add avocado or olive oil to your vitamin K intake.

• Engage in regular physical activity to support overall health and enhance vitamin K function.

• Implement stress management techniques, as chronic stress can negatively affect nutrient absorption.

Who Shouldn't Take Vitamin K?

Individuals on anticoagulant medications should speak to their doctor before adjusting their intake of vitamin K supplements or food intake. 

Disclaimer

Information in this blog is intended for educational purposes only. As always, talk to your provider about taking supplements.

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