Folic Acid Supplementation in Pregnancy: Dosage Guide

Folic acid is an important nutrient before conception and during early pregnancy. It helps the body make DNA and new cells and plays a key role in the development of the neural tube, which forms the baby's brain and spinal cord. Because the neural tube develops very early in pregnancy, often before you know you are pregnant, taking folic acid before conception is recommended.

This guide explains why folic acid is important during pregnancy, how much you usually need, when to start taking it, dietary sources and when a higher dose may be recommended.

Folic acid is the synthetic form of folate, a B vitamin. Your body needs folate to make DNA, support cell division and produce healthy red blood cells.

During the early weeks of pregnancy, adequate folate is particularly important for the development and closure of the neural tube. If the neural tube does not close properly, it can result in neural tube defects (NTDs), including spina bifida and anencephaly.

The neural tube develops very early in pregnancy, which is why folic acid should ideally be started before conception rather than after a positive pregnancy test.

Folate also contributes to normal blood formation and cell growth throughout pregnancy.

For most women who are planning a pregnancy or could become pregnant, the recommended daily dose is 400 micrograms (mcg) of folic acid.

The table below summarises the usual recommendation and situations in which a higher dose may be prescribed.

A 5 mg dose is not routinely recommended for everyone. Your doctor may prescribe it if you have certain risk factors, such as a previous pregnancy affected by an NTD or certain medical conditions or medicines that increase the risk of NTDs.

Do not start a 5 mg dose on your own. Your doctor can determine whether you need a higher dose and how long you should take it.

Ideally, start taking 400 mcg of folic acid before conception. If you are planning a pregnancy, starting at least one month before conception is recommended, and starting earlier can help ensure that you are taking it consistently before pregnancy occurs.

Continue taking folic acid through the first 12 weeks of pregnancy. This covers the period when the neural tube is developing.

If you did not take folic acid before becoming pregnant, start as soon as you find out that you are pregnant and speak with your doctor about the appropriate dose.

Your doctor may recommend continuing folic acid beyond the first 12 weeks in certain circumstances. Follow the duration advised for your individual needs.

Folate occurs naturally in a variety of foods. Including these foods as part of a balanced diet can help you meet your nutritional needs during pregnancy.

Good sources include:

• Green leafy vegetables such as spinach and fenugreek leaves
• Pulses and legumes such as chickpeas, kidney beans and moong dal
• Broccoli and other green vegetables
• Citrus fruits such as oranges and sweet lime
• Peanuts and other nuts
• Eggs
• Fortified foods and cereals

Liver contains folate but is generally avoided during pregnancy because it contains high levels of vitamin A, which can be harmful to the developing baby.

A healthy diet provides natural folate, but dietary intake does not replace the recommended folic acid supplement for preventing neural tube defects.

Some pregnancies have a higher risk of neural tube defects. In these situations, your doctor may prescribe 5 mg of folic acid daily.

A higher dose may be recommended if you:

• Have previously had a pregnancy affected by an NTD.
• Have certain medical conditions that increase the risk of NTDs.
• Take certain medicines that affect folate metabolism, including some anti-epileptic medicines.
• Have another risk factor identified by your doctor.

The appropriate dose depends on your individual medical history. Do not take high-dose folic acid without medical advice.

Folic acid is generally well tolerated at recommended doses. However, tell your doctor or pharmacist about your medicines and supplements before starting a folic acid supplement.

This is particularly important if you take medicines that can affect folate metabolism or have a condition associated with vitamin B12 deficiency.

High doses of folic acid can correct the anaemia associated with vitamin B12 deficiency without correcting the underlying deficiency. This can allow neurological damage caused by vitamin B12 deficiency to continue unnoticed.

Methotrexate is another important medicine to discuss with your doctor. It interacts with folate pathways, and folic acid supplementation needs to be managed according to why methotrexate is being used.

If you have anaemia or symptoms that could indicate vitamin B12 deficiency, your doctor may recommend appropriate blood tests.

Most people tolerate recommended doses of folic acid well. Some may experience mild side effects such as:

• Nausea
• Bloating
• Stomach discomfort
• Loss of appetite

Taking the supplement with food may help if it causes stomach discomfort.

Seek medical attention if you develop signs of a serious allergic reaction, such as swelling of the face, lips or throat, difficulty breathing or a severe skin reaction.

If you develop persistent or concerning symptoms after starting a supplement, speak with your doctor or pharmacist.

Folic acid is particularly important before conception and during the first 12 weeks of pregnancy because it supports the development and closure of the neural tube. For most women, 400 mcg daily is recommended before conception and through the first 12 weeks of pregnancy.

Some women need a higher 5 mg dose because of specific risk factors. This dose should be prescribed by a doctor. If you are planning a pregnancy, are pregnant or have questions about the right dose for you, speak with your doctor or pharmacist.