Prenatal Vitamins

Written by

Rob Buist

Published on


Most women know that is important to take Vitamins during their pregnancy. Most of the scientific evidence – and the consequent recommendations by health authorities – on this topic relates to taking a Folic Acid supplement.

Why Folic Acid?

Folate is Vitamin B9 and Folic Acid is a form of folate, as is folinic acid. Folic Acid is a synthesised form of folate (it is oxidised) and it enters your tissues more easily than folate. There is very good scientific evidence that taking a supplement of at least 400 micrograms (mcg) of Folic Acid before conception (preferably for at least one month) and for the first twelve weeks of pregnancy significantly reduces the risk of your baby suffering from a Neural Tube Defect (NTD). NTDs are abnormalities of the brain and spinal cord and they include Spina Bifida. The association between Folic Acid and NTDs is consistent with our understanding that folate is critical to the development of what we call the baby’s Neural Tube in very early pregnancy.

Now some commentators are critical of the fact that Folic Acid is a “chemically synthesised” form of folate but it is important to remember that:

  • There is extremely little difference in structure between Folic Acid and folate,
  • Folic acid enters tissues more readily than folate, and
  • The scientific studies that have confirmed the benefit of Folic Acid used, well, Folic Acid.

In Australia it is recommended that women take a supplement that includes at least 500 mcg (0.5 mg) of folic acid per day. Women with a previous or family history of giving birth to a baby with an NTD should take at least 5 mg per day. Women who are obese, suffer from diabetes and are on certain medications should also take 5 mg of folic acid per day.


The developing brain of your baby requires optimal levels of thyroxine for full maturation and those thyroxine levels are dependent upon your intake of iodine. Until well into the third trimester your baby is dependent on thyroxine that crosses the placenta from your blood. Now that iodised salt is rarely used iodine deficiency is much more common than was previously thought. For this reason the Australian National Health and Medical Research Council (NHMRC) recommends that pregnant women – with the exception of those with some thyroid conditions – take an iodine supplement of 150 mcg per day.

So it was the proven benefits of Folic Acid and Iodine supplementation that got the whole “pregnancy vitamins” thing going. Soon afterwards people began to think about other vitamins and minerals that could be added to Folic Acid to make a “perfect” pregnancy vitamin supplement. These vitamins and minerals include:

  • Vitamin D3,
  • Iron, and 
  • Calcium.

It is important to understand that there is not the same level of scientific evidence to support addition of these elements to a pregnancy vitamin supplement but they are likely to be beneficial if you are deficient in any of them. For example:

  • Women with dark skin or those who spend a long time indoors may benefit from a Vitamin D supplement.
  • Vegetarians are likely to benefit from an Iron supplement, and
  • Women with low intakes of dairy products should take a calcium supplement.  

Omega – 3s, or Fish Oil supplements

Omega-3s are often included in pregnancy vitamins but there is limited evidence supporting their use, aside from a small reduction in the risk of preterm birth. In any case Omega-3 supplements vary in quality and one small serve of oily fish provides up to two weeks’ worth of Omega-3s.

Warning: Vitamin A

Vitamin A supplementation of more than 700 mcg may cause fetal abnormalities so it is important that whatever supplement you do take does NOT contain significant amounts of Vitamin A.

Source: Various Authors. Nutrition. O and G Magazine Vol 14 no 3, 2012. Royal Australian and New Zealand College of Obstetrics and Gynaecology.