Folic acid is used to: treat or prevent folate deficiency anaemia. help your baby's brain, skull and spinal cord develop properly in pregnancy, to avoid development problems (called neural tube defects) such as spina bifida. Dose for treating folate deficiency anaemia To treat anaemia, the usual dose for adults and children over 1 year old is 5mg, taken once a day. Sometimes the dose is increased to 15mg a day. If your child is under 12 months old, the doctor will use your child's weight to work out the right dose.