The big 3 of pregnancy supplements

Folic acid

Maternal folic acid deficiency has been linked to the development of neural tube defects (NTD) such as spina bifida, which is why it remains one of the most important pregnancy supplements – in fact, it is recommended that folic acid supplementation is taken for at least a month before conception, and continued for the first trimester of pregnancy to assist the prevention of NTD.

Fast facts

  • There is no evidence that continued folic acid supplementation after the first trimester is beneficial.
  • The recommended dose of folic acid supplementation during pre-conception is at least 0.4 mg daily.
  • A 5mg daily dose of folic acid is recommended where there is an increased risk of NTD (for example: women who are obese, those using anti-convulsant medication, those with existing type 2 diabetes, those with a previous history of a child with NTD or a family history of NTD).


Severe maternal iodine deficiency has been linked to pregnancy loss and impaired mental and physical development in the foetus. Mild to moderate iodine deficiency during pregnancy adversely affects infant thyroid function and may affect mental development.

Fast facts

  • Iodine supplementation (150mcg daily) is recommended before a woman becomes pregnant – this helps optimise foetal development.
  • Iodine supplementation should be continued for the duration of the pregnancy and as long as a woman is breastfeeding.
  • Women with diagnosed pre-existing thyroid conditions should seek advice from their doctor before taking any iodine supplements.
  • An excess of iodine can impact thyroid function, so women who consume seaweed soup on a daily basis should seek advice before taking iodine supplementation.

Omega-3 fatty acids

Omega-3 fatty acids are important for foetal development, including brain development.

Fast facts

  • Australian and New Zealand dietary guidelines recommend two to three servings of oily fish (eg. salmon, tuna) per week to provide adequate amounts of omega-3 fatty acids.
  • Too much mercury can harm the developing nervous system of babies, and while most fish in Australia and New Zealand are low in mercury, it does vary from fish to fish so it’s a good idea to be mercury savvy.

Fish with higher levels of mercury include:

  • Shark
  • Ray
  • Swordfish
  • Barramundi
  • Gemfish
  • Orange roughy
  • Ling
  • Southern bluefin tuna

Fish with lower mercury levels include:

  • Shellfish including prawns, lobsters and oysters
  • Salmon
  • Canned tuna

Other vitamins and minerals

As well as keeping up intake of folic acid, iodine and omega-3 fatty acids, pregnant women should maintain adequate levels of other vitamins and minerals. The key players?

  • Calcium – required for the normal development and maintenance of the skeleton, the recommended dietary intake of calcium for pregnant women is 1300mg per day for those aged under 18 years and 1000mg for those aged 19–50 years.
  • Iron – iron requirements increase during pregnancy and maternal iron deficiency anaemia has been shown to adversely affect foetal brain development, increasing the risk of poor cognitive, as well as poor motor and behavioural development in the offspring. Children of iron-deficient mothers are also more likely to have low iron stores and be susceptible to iron deficiency. Iron levels are generally monitored throughout pregnancy, so deficiencies can be quickly diagnosed and treated. As well as taking supplements, food sources of iron include wholegrain cereal products fortified with iron (you can check out the RDI your cereal meets on the food label), and red meats and leafy greens are also good food sources of iron, as are licorice and prune juice!
  • Zinc – essential for growth and neurobehavioural development, zinc requirements increase during pregnancy. Maternal zinc deficiency has been associated with growth retardation and congenital abnormalities (including neural tube defects), low birth weight and premature delivery, as well as problems with neurobehavioural and immunological development in the foetus.
  • Vitamin B12 – B12 is essential for cell function and neurological function, including neural tube development, and the recommended daily intake of vitamin B12 is 6mcg/day.
  • Vitamin D – severe maternal deficiency has been associated with rickets, and decreased foetal growth. It may also affect bone mineralisation in adulthood at the time of peak bone mass.

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