Excess vitamin B12 and pregnancy

Excess vitamin B12 during pregnancy can increase the risk of health complications for the baby. Vitamin B12 is an essential vitamin that your body needs to perform vital functions. This vitamin dissolves in water and leaves the body daily through urine. Your liver can store vitamin B12 for several years.
Health guidelines have not established an upper safety limit for vitamin B12, and it is generally considered safe even when taking very high-dose supplements. However, having much more vitamin B12 in the body than you need during pregnancy can increase the risk of health complications for the baby, research shows.

This article has been verified by a medical professional

Impact of excess vitamin B12 on pregnancy

Very high levels of vitamin B12 during pregnancy can almost triple the risk that the child develops autism spectrum disorder. In pregnant women who have both excess vitamin B12 and excess folate, the risk for autism increases 17.6 times.

Autism is a developmental disability that affects a person’s social skills, nonverbal communication, and behavior. Signs of autism usually become apparent around age 2 or 3, but in some cases, it can be diagnosed at 18 months. Asperger syndrome is a form of autism.

Potential causes of excess vitamin B12

Excess vitamin B12 is generally due to taking high-dose supplements. It may happen following treatment with injectable vitamin B12 for a deficiency or vitamin B12 deficiency anemia. Eating a lot of meat can also raise your vitamin B12 levels.

High vitamin B12 is also found in people with the following health conditions:

• Blood disorders (leukemia, polycythemia vera, and hypereosinophilic syndrome)
• Liver disease
• Diabetes
• Kidney failure

Symptoms of excess vitamin B12

High doses of vitamin B12 may cause the following symptoms:

• Headache
• Nausea
• Vomiting
• Diarrhea
• Fatigue
• Tingling in the hands and feet

Diagnosis of excess vitamin B12

You can find out your vitamin B12 status through a blood test. Because excess vitamin B12 can be a sign of other health conditions, you may have additional lab tests done.

Treatment

To reduce your vitamin B12 intake and get to a safe level for pregnancy, you can adjust your diet. Animal products, including fish, shellfish, meat, poultry, eggs, and dairy are high in vitamin B12, so you can switch to more plant-based foods. Some breakfast cereals are fortified with this vitamin, so check the nutritional label before buying. Additionally, you should stop taking vitamin B12 supplements.

You can work together with a LEVY nutritionist to come up with a personalized meal plan and ensure you are getting all the right amounts of the necessary vitamins to boost your fertility and protect your baby’s health.

If your doctor finds that you have an underlying health condition linked to your high vitamin B12 level, you will have treatment to manage the condition. For instance, diabetes is treated with insulin and/or diabetes medications like metformin, along with lifestyle changes, which help to control blood sugar levels and significantly improve fertility.

• Ermens A A M et al.: Significance of elevated cobalamin (vitamin B12) levels in blood. Clin Biochem. 2003;36(8):585-590.
• Vitamin B-12. Mayo Clinic. Accessed 11 January 2023.
• Vitamin B12. National Institutes of Health – Office of Dietary Supplements. Accessed 11 January 2023.
• Vitamin B12. MedlinePlus. Accessed 12 January 2023.
• Raghaven R et al.: Maternal Multivitami Intake, Plasma Folate and Vitamin B12 Levels and Autism Spectrum Disorder Risk in Offspring. Paediatr Perinat Epidemiol. 2018;32(1):100-111.
• Morales-Gutierrez J et al.: Toxicity induced by multiple high doses of vitamin B12 during pernicious anemia treatment: a case report. Clin Toxicol (Phila). 2020;58(2):129-131. 
• Too Much Folate in Pregnant Women Increases Risk for Autism, Study Suggests. Johns Hopkins Bloomberg School of Public Health. Accessed 12 January 2023. 
• What Is Autism? Autism Speaks. Accessed 12 January 2023. 
• What Is a Vitamin B-12 Test? Healthline. Accessed 12 January 2023. 
• What is the purpose of a vitamin B-12 level test? Medical News Today. Accessed 12 January 2023.