Vitamin B12

Date: November 2024, Version 3

Quick take

Vitamin B12 supplements can be used in pregnancy but should not be needed unless you are at risk of B12 deficiency (e.g. because of a vegan diet) or have had a B12 deficiency diagnosed with a blood test.

What is it?

Vitamin B12 (hydroxocobalamin, cyanocobalamin) occurs naturally in eggs, meat and dairy-based food, and is also present in certain vitamin supplements including some designed for use in pregnancy. A well-balanced diet should provide adequate vitamin B12 for most people.

Benefits

What are the benefits of using vitamin B12 in pregnancy?

It is important to correct a diagnosed vitamin B12 deficiency for the health of both you and your baby.

Taking vitamin B12 can help prevent and treat anaemia (where oxygen-carrying red blood cells do not function correctly) and symptoms including extreme tiredness, weakness, mouth ulcers, pins and needles, and eyesight, psychological, and memory problems. Without treatment, some of these problems can become permanent.

Vitamin B12 treatment can help with the normal development of your baby in the womb. This is because a B12 deficiency in pregnancy can increase the chance of your baby having a neural tube defect such as spina bifida.

Risks

What are the risks of using vitamin B12 in pregnancy?

There are no known risks.

Alternatives

Are there any alternatives to using vitamin B12 in pregnancy?

No. If vitamin B12 treatment is needed to correct a deficiency it is important that you take it to avoid long-term health complications for you and your baby.

No treatment

What if I prefer not to take medicines during pregnancy?

If you need vitamin B12 treatment, it should not be avoided, as vitamin B12 deficiency poses risks to both you and your baby.

Will I or my baby need extra monitoring?

As part of routine antenatal care in the UK, you will be invited for a very detailed scan at around 20 weeks of pregnancy to check your baby’s development. No further scans to check for birth defects will be required due to use of vitamin B12. If you have had a severe vitamin B12 deficiency in early pregnancy you may be offered more detailed scanning of your baby’s spine to check the neural tube.

Are there any risks to my baby if the father has used vitamin B12?

There is currently no evidence that vitamin B12 used by the father can harm the baby through effects on the sperm, and we would not expect any adverse effects.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet, please discuss them with your health care provider. They can access more detailed medical and scientific information from www.uktis.org.

How can I help to improve drug safety information for pregnant women in the future?

Our online reporting system (MyBump Portal) allows women who are currently pregnant to create a secure record of their pregnancy, collected through a series of questionnaires. You will be asked to enter information about your health, whether or not you take any medicines, your pregnancy outcome and your child's development. You can update your details at any time during pregnancy or afterwards. This information will help us better understand how medicines affect the health of pregnant women and their babies. Please visit the MyBump Portal to register.

General information
Sadly, miscarriage and birth defects can occur in any pregnancy.

Miscarriage occurs in about 1 in every 5 pregnancies, and 1 in every 40 babies are born with a birth defect. This is called the ‘background risk’ and happens whether medication is taken or not.

Most medicines cross the placenta and reach the baby. For many medications this is not a problem. However, some medicines can affect a baby’s growth and development.

If you take regular medication and are planning to conceive, you should discuss whether your medicine is safe to continue with your doctor/health care team before becoming pregnant. If you have an unplanned pregnancy while taking a medicine, you should tell your doctor as soon as possible.

If a new medicine is suggested for you during pregnancy, please make sure that the person prescribing it knows that you are pregnant. If you have any concerns about a medicine, you can check with your doctor, midwife or pharmacist.

Our Bumps information leaflets provide information about the effects of medicines in pregnancy so that you can decide, together with your healthcare provider, what is best for you and your baby.