Peer Reviewed
Focus on pregnancy

Micronutrient supplementation – supporting a healthy pregnancy and baby

Jenna L Hollis BND, PhD, Tessa Delaney BND, PhD, Phoebe Holdenson Kimura MB BS, FRACGP, MPH, Bianca Cannon MB BS(Hons 1), FRACGP, MPH, Michelle Guppy MB BS, FRACGP, MPH, Susan De Jersey BHlthSci(N&D), BAppSci(HMS), GCertDiabetesMgmt, MPH, PhD, Elizabeth J Elliott MD, MPhil, MB BS, FRACP, FRCPCH, FRCP, Melanie Kingsland BAppSci, MMedSci, PhD

GPs play an important role in providing guidance on appropriate nutrient supplement use for women before and during pregnancy and while breastfeeding. Micronutrient supplement use by these women lowers their risk of some adverse pregnancy health outcomes and supports the growth of the developing baby.

Key Points
    • Key opportunities to discuss nutrient supplements with women are at the preconception visit, first antenatal visit and first postnatal visit.
    • Although most pregnant women are aware of the need for nutrient supplements in pregnancy, there are much lower levels of specific knowledge of the recommended nutrients and their dose and timing.
    • Some multinutrient pregnancy-specific supplements do not contain the recommended combination of micronutrients or doses for all women (without additional nutrient needs) before and during pregnancy, or while breastfeeding.
    • Only folic acid and iodine supplements are recommended for all women before and during pregnancy. Iodine supplementation should be continued while breastfeeding.
    • Other nutrient supplements, such as iron, calcium, vitamin B12, vitamin D and omega-3 fatty acids, may also be recommended depending on a woman’s individual needs, dietary deficiencies and health.
    • Screen for iron-deficiency anaemia routinely at the first antenatal visit and at 28 weeks’ gestation to determine if iron supplementation is required.

Micronutrients have important influences on the health of pregnant women and their children, including lowering the risk of some adverse pregnancy health outcomes and supporting the growth of the developing baby.1 The recommended dietary intake for micronutrients, such as folate and iodine, is higher during preconception, pregnancy and breastfeeding.2 Normal eating habits and the fortification of foods in Australia usually do not meet these increased nutrient needs.3-5 Therefore, supplementation for some nutrients is recommended to support a healthy pregnancy and baby.6,7


In Australia, GPs are important providers of preconception, antenatal and postnatal care for women. Between 85 and 92% of women of reproductive age (15 to 44 years) report seeing a GP in the previous 12 months, and between 6 and 17% specifically seek care from their GP for preconception or family planning support.8 GPs also provide antenatal care to almost 90% of women in early pregnancy and to 28% throughout their pregnancy.9 For most pregnant women, GPs are the first point of health care contact,10 including for the 40% of women who experience an unplanned pregnancy.11 GPs are integral providers of advice and support for nutrient supplement use for women who are planning a pregnancy, during pregnancy and while breastfeeding. However, Australian healthcare providers, including GPs, report barriers to providing such care, including uncertainty as to whether supplementation is needed when there is mandatory food fortification (e.g. for folate and iodine) in Australia, and lack of knowledge on what to recommend, including the appropriate dose and duration, and additional considerations required for individualised recommendations.12,13

Studies of GP provision of nutrient supplements for women during pregnancy and breastfeeding report highly variable findings. In three studies that included a total of 142 GPs in Australia, 52% reported recommending folic acid supplements to pregnant women, 66% reported recommending iodine supplements to women planning a pregnancy,26 to 84% to women during pregnancy and 45% to women who are breastfeeding.13-15

This article provides an overview of the latest evidence and clinical practice guidelines to support GPs in providing recommendations on nutrient supplements to women before and during pregnancy and while breastfeeding.

What proportion of women use nutrient supplements before and during pregnancy and while breastfeeding?

In Australia, nutrient supplement use during preconception, pregnancy and breastfeeding is highly variable. Although most pregnant women are aware of the need for nutrient supplements in pregnancy, there are much lower levels of specific knowledge of the recommended nutrients, their dose and timing.16 Adherence to the recommendations is also low.16 Although one in three pregnant women in Australia report taking a multinutrient supplement (containing one or more micronutrients),17 these may not provide the recommended nutrients or doses required for the particular stage of pregnancy or in the context of diagnosed health conditions and nutrient deficiencies.18

In the Australian Longitudinal Study on Women’s Health, self-reported data on nutritional supplement use in 485 women of reproductive age was recorded prospectively.19 Before conceiving, about half of the women who later became pregnant reported taking a folic acid-containing supplement and 37% took an iodine-containing supplement.19 Although up to 39% took an iron- containing supplement prior to pregnancy, only 23% reported having a diagnosed iron deficiency,19 which may indicate a need for iron supplementation.6,20

During pregnancy, about nine out of ten women in Australia report taking a folic acid-containing supplement, and eight out of ten take an iodine-containing supplement.16,21 Other supplements often consumed in pregnancy include iron (30%), vitamin D (23%), calcium (13%) and fish oil/omega-3 fatty acids (12%), although it is unclear if supplementation was recommended based on a diagnosed nutrient deficiency, dietary pattern or clinical indication.22

During breastfeeding, 45% of women in Australia report taking an iodine-containing supplement.23 Of concern, many women who took iodine supplements during pregnancy ceased taking supplements when breastfeeding.23 Most women who continue to take nutrient supplements while breastfeeding report consuming a multivitamin that contributes only half the recommended dose of iodine.23


Adherence to the correct dose and duration of supplements across preconception, pregnancy and breastfeeding is low. In a 2013 Australian study of 857 women, only one in five fully adhered to recommendations on both the dose and duration of folic acid and iodine supplementation specific to the stage of pregnancy.16 Women who were aware of the recommended duration of supplements and who planned their pregnancy were more likely to adhere to the recommendations.16

There is limited information on the use of nutrient supplements among Aboriginal and Torres Strait Islander women who are pregnant or breastfeeding. This may be a consequence of not including Aboriginal and Torres Strait Islander people in designing and conducting research which could ensure that culturally appropriate research methods are used.24-26 In a 2014-19 cohort study of 152 Aboriginal and Torres Strait Islander pregnant women or pregnant women carrying an Aboriginal and Torres Strait Islander baby in rural NSW, 51% of women reported taking a folic acid supplement during pregnancy.27 Barriers to accessing health care for Aboriginal and Torres Strait Islander women, including historical trauma arising from colonisation, systemic racism and socioeconomic disadvantage, are well documented.28 These factors, along with cost and access to nutrient supplements, may contribute to lower rates of supplement use by Aboriginal and Torres Strait Islander women.28 General multinutrient supplements may be chosen by women over pregnancy-specific nutrient supplements due to concerns about cost; however, these general multinutrient supplements often have insufficient quantities of nutrients recommended for pregnancy.29

About 90% of pregnant women in Australia want support and advice from their healthcare providers, including their GPs, on which nutrient supplements are required for a healthy pregnancy and while breastfeeding.16,21,30 Of concern, women often report seeking advice on supplements from the internet; however, over 40% of websites with information on pregnancy nutrient supplements have been shown to be inaccurate or misleading.31 Systematic review evidence shows that advice and support from healthcare providers, including GPs, during the preconception and antenatal periods improves women’s adherence to nutrient supplement recommendations.32,33

What are the impacts of nutrient supplements on the pregnancy, mother and child?

Supplementation of some nutrients (e.g. folic acid and iodine) before conception, during pregnancy and while breastfeeding is associated with a range of positive pregnancy and health outcomes. In the absence of a diagnosed deficiency or medical need, the current available evidence suggests that other nutrient supplements provide no benefit and may have adverse consequences. Evidence from systematic reviews and meta-analyses on the association between supplementation of key micronutrients and positive health outcomes during preconception, pregnancy and breastfeeding is summarised in Table 1.34-41

The association between micronutrients and other pregnancy and health outcomes has recently been investigated. For example, emerging research has examined the association between vitamin D deficiency and autism spectrum disorders.42-45 The current evidence base is primarily from animal studies or observational studies in humans with small sample sizes with inconsistent evidence of an association or causal relationship.42-45 Currently, there is insufficient evidence to recommend vitamin D supplements to all pregnant women to reduce the risk of autism spectrum disorders in children.45


What nutrient supplements are recommended?

The Australian Government Department of Health and Aged Care, The Royal Australian College of General Practitioners and The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (as well as other Australian state, hospital and medical body guidelines) recommend folic acid and iodine supplementation for all women who are planning a pregnancy or are pregnant, and iodine supplementation for breastfeeding women (Table 2).6,20,46-51 Other nutrient supplements, such as iron, calcium, vitamin B12, vitamin D and omega-3 fatty acids, may also be recommended depending on a woman’s individual needs, dietary deficiencies and health.6,20,47 In the absence of a diagnosed deficiency, nutrient supplements of vitamin A, C and E are not recommended because they provide little or no benefit and may have adverse health consequences.6,20 The specific populations for whom additional nutrient supplements are recommended according to key national, state, hospital and medical/professional body guidelines are included in Table 3.6,20,46,47,49,52-54 Some guidelines currently differ with regards to recommendations for dose, duration, routine screening and populations for whom nutrient supplementation are recommended. Possible reasons for these differences are that guidelines may not have been updated to reflect the most recent evidence, low- or varying-quality evidence has been interpreted differently and clinical judgement has been used when interpreting the evidence or contextualising to the Australian population. Some guidelines also do not cover all preconception, pregnancy and breastfeeding periods. The full list of guidelines reviewed for this article are included in Box 1 and provide more information on recommended assessment, management and monitoring for each nutrient supplement.

Many women take multinutrient supplement(s) before or early in pregnancy and although these supplements contain many of the individual vitamins and minerals presented in Table 2 and Table 3, the dose may be insufficient or exceed nutrient supplement recommendations.18 It is important to ask what nutrient supplements (including the brand, dose and timing) the women is already taking or planning to take in pregnancy, to inform the provision of advice on nutrient supplementation.6

What is the GP’s role in supporting women to take nutrient supplements?

The Australian Department of Health Clinical Practice Guidelines for Pregnancy recommend the following three elements of care to support women to take nutrient supplements (Box 2).6

  • Assess current nutrient supplement intake and any health and dietary considerations required to guide clinical decisions on individualised recommendations.
  • Advise and discuss recommended nutrient supplements and benefits for the pregnancy and baby.
  • Refer to a specialist, such as a dietitian, obstetrician or obstetric medicine specialist, if further advice and support is needed.

In the primary care setting, a collaborative conversation that invites the views of a patient, with tailored discussions based on question-answer sequences and joint decision-making when planning actions to overcome barriers, is more likely to lead to patient behaviour change compared with advice-giving only.55 Pregnant women commonly cite forgetting to take supplements and not knowing the recommended type, dose and timing of nutrient supplements required (or which supplement brand types provide their nutrient requirements) as barriers to adhering to supplement recommendations.21,56 Supporting women to identify their personal barriers to supplement use and checking that they have correctly understood what is being recommended (including the dose, timing, frequency and duration of therapy) may support adherence.



GPs play an important role in providing guidance on appropriate nutrient supplement use for women before and during pregnancy and while breastfeeding. Nutrient supplement use around the pregnancy life stage is effective in optimising health outcomes for pregnant women and their babies. Recommendations for universal and selective supplementation are included in a range of resources (Box 1), but management needs to consider the woman’s nutritional and health status and be individualised and based on clinical judgement.

Further considerations

In this article, we refer to pregnant ‘women’ to reflect research evidence, while acknowledging that transgender and gender-diverse people can also become pregnant. Engaging with partners and families is important in supporting women to meet their nutrient supplement needs and should be considered when providing care. This article summarises current recommendations on nutrient supplements from a range of national, state, hospital and medical/professional body guidelines at the time of writing the article. Other guidelines with nutrient supplement recommendations may exist and should be considered where clinically and locally relevant. Recommended care for dietary food intake, including the five food groups, probiotics, food safety and weight during pregnancy57 are outside the scope of this article and will be summarised in other articles in Medicine Today.  MT

COMPETING INTERESTS: Dr Hollis is a Clinical and Health Service Research Fellow funded by Hunter New England Local Health District Partnerships, Innovation and Research through the HNELHD Clinical and Health Service Research Fellowship Scheme. Associate Professor de Jersey is an Associate Professor in the Centre for Health Services Research at the University of Queensland funded through the Metro North Health Clinician Research Fellowship Scheme. Professor Elliott was supported by a Medical Research Futures Fund  Next Generation Fellowship (APP1135959) and a National Health and Medical Research Council of Australia Leadership Fellowship (No 2026176).  Dr Kingsland is Research Fellow with the University of Newcastle funded through a grant from The Australian Prevention Partnership Centre (TAPPC) and a Program Manager with Hunter New England Population Health. Dr Cannon, Dr Kimura, Dr Guppy, Dr Delaney: None.


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