The Benefits and Importance of B12 During Pregnancy

Vitamin B12 is a water-soluble vitamin required at every stage in life, most critically during pregnancy.

B12 plays a crucial role in DNA synthesis, methylation reactions, and maintenance of genomic stability. During pregnancy, it is particularly necessary for neural myelination, cognitive function, red blood cell formation, and the development of the central nervous system.

Low B12 status is common in pregnant mothers, particularly in resource-poor environments and in multiple pregnancies. Tissue stores of B12 are depleted, leading to impairments in B12-dependent pathways and, subsequently, increased levels of homocysteine and methylmalonic acid.

Brain development begins from conception, and pregnancy is a period of rapid growth and development for the child’s brain. Poor vitamin B12 status during pregnancy and infancy has been linked to harmful effects on the fetus, including poor neurodevelopment, low birth weight, and a higher risk of neural tube defects.

This article will discuss the importance of B12 during pregnancy and its many benefits for both the mother and the developing fetus. We will explain how to identify a B12 deficiency and how to support B12 levels through diet and supplementation during pregnancy.

The importance of maintaining healthy B12 levels before conception and during pregnancy cannot be emphasized enough. B12 has a fundamental role in the most important aspects of human development, including neural myelination, brain function, and growth.

The most important function of vitamin B12 is to accomplish DNA synthesis, which is necessary for cell division and proliferation.

Vitamin B12 works alongside folate as a methyl donor in one-carbon metabolism, which is essential for DNA synthesis and epigenetic regulation, and, therefore, in fetal growth.

Impairment in the one-carbon transfer can have profound effects on cell proliferation, growth, and function. This can lead to poor fetal growth with immediate and long-term consequences for the baby.

B12 is required for the synthesis of methionine from homocysteine. The activated form of methionine, S-adenosylmethionine (SAM), is the major methyl group donor involved in methylation reactions, including methylation of DNA and RNA.

If methylation reactions in the central nervous system cannot occur, methylation of myelin basic protein in the central nervous system (and peripheral nervous system) may be impaired. Myelin production is essential for multiple brain systems and is closely connected to neurodevelopment and subsequent cognitive functioning.

Iron requirements gradually increase during pregnancy, leading to higher amounts of erythropoietin (EPO) and reticulocytes, and changes in erythrocyte size and density.

Vitamin B12 is required for erythropoiesis, and deficiency of vitamin B12 (and folate) often leads to megaloblastic anemia or iron deficiency anemia. Anemia specifically caused by vitamin B12 deficiency occurs in 10–28% of uncomplicated pregnancies.

Vitamin B12 deficiency is associated with negative outcomes for both the mother and baby, including developmental anomalies, miscarriage, preeclampsia, low birth weight, intrauterine growth restriction (IUGR), and neural tube defects.

Vitamin B12 deficiency can have a range of hematological, gastrointestinal, psychiatric, and neurological symptoms. These symptoms may include:

• Macrocytic anemia (displaying as fatigue and pallor)
• Jaundice (increased hemolysis caused by impaired red blood cell formation)
• Neurological symptoms, including:

1. Vision problems
2. Memory loss
3. Paraesthesia
4. Poor physical coordination
5. Peripheral neuropathy

• Lethargy
• Light-headedness
• Breathlessness
• Palpitations
• Glossitis (swollen and inflamed tongue)
• Diarrhea
• Headaches
• Mental health issues, including depression and anxiety

Vitamin B12 deficiency may be more prevalent in those with MTHFR mutations and should be monitored carefully. Low B12 can impair cell multiplication and increase the risk of accumulated homocysteine, both of which can have negative pregnancy outcomes.

Moderate hyperhomocysteinemia and the C677T mutation are associated with an increased risk of recurrent pregnancy loss.

The body’s need for B12 increases substantially during pregnancy, particularly in fetal neurological development. The WHO and US National Institutes of Health recommend that pregnant women take 2.6mg of B12 daily.

Taking the right amount of B12 is vital. As explained above, B12 deficiency in pregnancy can increase the risk of elevated homocysteine, which has been associated with miscarriage and pregnancy loss.

Neural tube defects are one of the most common outcomes of deficient or inadequate vitamin B12 during pregnancy. Deficits in vitamin B12 have negative consequences on brain development during infancy, as well as abnormal behavior and development due to disruptions to myelination and inflammatory processes.

Low vitamin B12 may increase the risk of postpartum depression in women.

Most adults obtain their daily B12 requirements by eating foods such as beef, poultry, eggs, and dairy. Pregnant women are also encouraged to eat plenty of B12-rich foods. However, dietary sources may not always be enough due to the increased demands for B12 during pregnancy. A woman’s dietary preferences and appetite may also change during pregnancy.

The best way to ensure that both mother and baby are receiving adequate B12 during pregnancy is through supplementation. A quality prenatal multivitamin helps to fill in any gaps in the diet and provides all the nutrients that are so vital during pregnancy.

Dietary B12 is exclusively available from animal sources. Some plant-based foods may be fortified with B12, but consumers should be aware that these contain a synthetic form called cyanocobalamin. 

The best B12 foods to eat during pregnancy include:

• Cooked poultry (preferably fresh-cooked and organic; avoid processed chicken)
• Fish (especially wild salmon, cod, skipjack and canned light tuna, and other low-mercury species)
• Shrimp
• Eggs
• Grass-fed organic beef
• Dairy products, including yogurt, milk, swiss cheese, and cottage cheese
• Fortified foods, including cereals, bread, milk, and soy products

Supplementing with vitamin B12 ensures that both mother and baby get the necessary nutrients. Vegans, vegetarians, and those with malabsorption disorders or MTHFR mutations are encouraged to supplement with B12.

When choosing a quality vitamin B12 supplement, it’s important to check the nutrient's form. The three natural forms of B12 are methylcobalamin, hydroxocobalamin, and adenosylcobalamin. These are also the forms most easily absorbed and utilized by the body.

Most prenatal multivitamins include vitamin B12 alongside other important nutrients, including folate and other B vitamins, vitamin D, minerals, antioxidants, iodine, and omega-3.

Methyl-Life® specializes in premium supplements for those with heightened needs. The Methyl-Life® Pregnancy Bundle includes three supplements suited to pregnancy and preconception: Vitamin B12 (Hydroxocobalamin 2.5mg), a Chewable Methylated Multi, and L-Methylfolate 2.5mg. Taken together, these products provide the nutrients required to support fetal development and maternal health in their most bioavailable forms.

Brain growth is very rapid during the first two years of life, particularly in the cortex, which is associated with higher-order thinking. Increasing B12 intake during breastfeeding is crucial in order to support this neurodevelopment.

Breastfeeding women must take at least 2.8 mcg B12 per day, with some sources recommending up to 5.5 mcg per day.

B12 deficiency in breastfed infants is often a result of the mother also being low in B12. In infants, vitamin B12 deficiency has been associated with demyelination and brain atrophy, along with many other health risks.

Again, supplementation is the best way to ensure these needs are met. Breastfeeding mothers are encouraged to take the most bioavailable form of B12 in order to restore and maintain their B12 status efficiently. Natural B12 (methylcobalamin, hydroxocobalamin, and adenosylcobalamin) is shown to be absorbed more efficiently than synthetic B12 (cyanocobalamin). These forms of B12 are available in supplements from the Methyl-Life® range, including Active 12 Complete and Vitamin B12 Hydroxocobalamin 2.5mg.