Multivitamins and pregnancy – before, during and after Part 1.

Women who are planning pregnancy often ask their GP about vitamin and mineral supplements. They want to make sure they are getting enough essential nutrients for a growing baby. However, there are so many supplements in pharmacies that it can be confusing.

This article with deal with nutritional needs in the preconception and antenatal period. Next weeks article will talk about specific brands available on the market in Australia.

A healthy and balanced diet is strongly recommended before, during and after pregnancy. However, many women in Australia do not get enough of certain nutrients as part of their general diet, and studies show that some key nutrients are essential for a baby’s growth and development.


The most important nutrient is folate (also called folic acid). Folate is needed for the development of a baby’s spine, brain and nervous system. Women who are low in folate have a higher rate of birth defects such as spina bifida. All women planning a pregnancy are strongly recommended to take additional folate supplements for at least 1 month (ideally 3 months) before falling pregnant. For most women, the minimum daily dose of folate supplementation is 0.4-0.5mg daily. However, some women should take a much higher dose. If you have diabetes, a BMI over 30, a condition that affects gut absorption (such as coeliac disease), a history of neural tube defects in your family, or if you are taking certain seizure medications, you should take 5mg daily (yes, this is 10 times higher than the standard dose!) Women who are pregnant with multiple babies (twins and triplets) are also advised to take a higher dose of folate.


Iodine is another essential nutrient that is important for a baby’s thyroid, brain development and overall metabolism. All women who are planning a pregnancy are advised to take an iodine supplement of 150mcg daily. If you have pre-existing thyroid problems, we recommend that you talk to your doctor about checking your thyroid is functioning well, have adequate thyroid hormone replacement, and manage your iodine requirements before falling pregnant.

Vitamin D

Vitamin D is important for the development of a baby’s bones. Vitamin D is a hormone created when your skin reacts to sunlight. Not all Australian women are low in Vitamin D, but you should take a supplement throughout your pregnancy if you are low. Groups at particular risk of Vitamin D deficiency are women who wear daily sunscreen, dark-skinned women, women who wear head coverings, women with BMI over 30, and women with a history of Vitamin D deficiency.
Vitamin D deficiency is very common even in non-risk groups, so most women should consider taking a supplement with 400 IU Vitamin D daily.
If you are low in Vitamin D (blood levels less than 50 nmol/L), talk to your doctor about the correct supplement for you. In general, pregnant women with levels 30-49 nmol/L should take 1000 IU daily and pregnant women with levels less than 30 nmol/L should take 2000 IU daily.


Many women enter pregnancy with low iron stores. As the pregnancy progresses, the baby will require more and more iron for the development of its red blood cells and brain growth. As a result, it is quite common for women to become iron deficient or anaemic in their third trimester. This can be dangerous for the baby and the mother. Most women lose blood during childbirth, and a major bleed can be life-threatening. Your GP will check your iron and red blood cell levels at your first antenatal visit and again at 26 weeks gestation and may advise supplements that are particularly suited to your circumstances. If you have borderline or low iron stores at the beginning of pregnancy, it is wise to choose a daily pregnancy multivitamin that is particularly high in iron.

Fish Oil

In recent years, the importance of Omega-3 fatty acids has become increasingly recognised. Omega-3 fatty acids are found in seafood and they are important for a baby’s brain and eye development. We now know that women who are low in Omega-3 fatty acids are at higher risk of having preterm labour, and their babies are more likely to be born small and require time in the Neonatal Intensive Care Unit. Prematurity is associated with an increased risk of disability. For that reason, we recommend taking a low-mercury fish oil supplement.

B12 and Calcium:

A final consideration is women who avoid certain food groups, especially vegetarian, vegan, or avoid dairy. Please tell your doctor about your dietary restrictions at your first antenatal appointment so they can arrange additional blood tests for you. You may be low in Vitamin B12 and/or calcium. B12 is important for a baby’s brain development. In general, vegetarian and vegan women are advised to take a B12 supplement of 2.6mcg daily during pregnancy. Calcium is important for a baby’s bone development, and low calcium intake is an independent risk factor for high blood pressure in pregnancy and preterm labour. All women should aim for 1000mg of daily calcium in pregnancy. This can be taken as a supplement if your diet is low in dairy products.

By Dr Corina Botan, YourGP@Lyneham.

Vitamin and Mineral Supplementation and Pregnancy, The Royal Australian and New Zealand College of Obstetricians and Gynaecologists, 2015.
Clinical Practice Guidelines: Pregnancy Care, The Royal Australian and New Zealand College of Obstetricians and Gynaecologists, 2018.