Condition management

It is important to complete an individual risk assessment for your patient and to apply the principles of prescribing during pregnancy when looking at the available information and making treatment decisions. Check to see if a risk assessment has already been completed.

Vitamin B₁₂ (cobalamin) is a water-soluble B vitamin essential for red blood cell formation, neurological function, and DNA synthesis. During pregnancy, vitamin B₁₂ is essential for normal growth and development of the foetus, in particular neural tube formation and brain development.

Supplementation of B vitamins, except from folic acid, is not needed during pregnancy, unless there is a known deficiency.

Guidelines

NICE CKS: Management of anaemia – vitamin B₁₂ and folate deficiency provides advice on the management of vitamin B₁₂ deficiency. The guideline discusses when to refer, dosing and monitoring during pregnancy.

NICE guideline: Vitamin B12 deficiency in over 12s: diagnosis and management [NG239] covers recognising, diagnosing and managing vitamin B12 deficiency in adults, including during pregnancy.

Treatment options

Continue vitamin B₁₂ replacement if treatment was started prior to conception.

Prescribers should seek urgent advice from a haematologist when treating vitamin B₁₂  deficiency anaemia during pregnancy.

Prescribing in pregnancy should be considered on an individual basis, particularly if there are unusual circumstances, such as complicated obstetric history.

Hydroxocobalamin and cyanocobalamin are naturally occurring analogues of vitamin B₁₂ used in the treatment of vitamin B₁₂ deficiency. Cyanocobalamin injection should not be prescribed as the NHS considers this formulation less suitable for prescribing.

With neurological involvement

Seek urgent advice.

Consider intramuscular hydroxocobalamin if specialist advice is not immediately available. Administer 1mg daily on alternative days until no further improvement, then 1mg every 2 months.

Without neurological involvement

Prescribe either intramuscular hydroxocobalamin or oral cyanocobalamin according to the recommendations in NICE CKS, depending on the cause of deficiency.

Oral cyanocobalamin

Consider a dose of at least 1mg a day when prescribing during pregnancy.

Intramuscular hydroxocobalamin

Administer at the same dose as for non-pregnant people, 1mg 3 times a week for 2 weeks, then 1mg every 2–3 months. A less frequent maintenance dose of 1mg twice-yearly can be administered for dietary vitamin B₁₂ deficiency.

Monitoring in pregnancy

Reassess symptoms 1 month after starting treatment, instead of the usual recommended period of 3 months.

The use of vitamin B₁₂ at any stage in pregnancy is not regarded as grounds for additional foetal monitoring.

Pregnancy outcome information

UK Teratology Information Service (UKTIS) has safety and pregnancy outcome information on the use of vitamin B₁₂ in pregnancy.

Patient information

UKTIS has corresponding BUMPS patient information on the use of vitamin B₁₂ in pregnancy.

NHS Medicines A-Z provides summary statements for the use of specific supplements in pregnancy: hydroxocobalamin and cyanocobalamin.

The Royal College of Obstetricians & Gynaecologists provides patient information on vitamin supplements in pregnancy.

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