During pregnancy, national and international health authorities advocate a higher intake of key vitamins and minerals to meet maternal and fetal needs. However, substantial cross country variation exists in the recommended micronutrient levels. This highlights cultural and dietary differences, but also the ongoing scientific discussions on the optimal diet during pregnancy.

Global nutrient recommendations in pregnancy

Health authorities across the globe recognize the need for an increased nutrient supply in pregnancy to support the health of the expectant mother and the unborn. Table 1 shows a selection of key micronutrient recommendations in pregnancy in three countries.1-3  In Annex I a more comprehensive table is available, which includes Malaysian recommendations.

Table 1 Selected nutrient recommendations in pregnancy for a selection of countries

  Netherlands US Malaysia
Vitamin A (mcg/day) 1000 770 800
Vitamin D (mcg/day) 10 15 5
Folic acid (mcg/day) 400 600 600
Vitamin B12 (mcg/day) 3.2 2.6 n/a
Calcium (mg/day) 1000 1000 1000
Iodine (mcg/day) n/a 220 200
Zinc (mg/day) 12-151 11-122 5.5-103
Iron (mg/day) 11-194 27 29-1005

1 12 in the first trimester, 15 in the second and third trimester.
2 11 in pregnant women aged  19-50 years, 12 in pregnant women aged 14-18 years
3 5.5 in the first trimester, 7.0 in the second and 10 in the third trimester
4 11 in the first trimester, 15 in the second and 19 in the third trimester
5 29 in the first trimester, 100 in the second and third trimester.

Zinc, calcium and iodine

Key minerals in pregnancy include zinc, iodine and calcium. Zinc contributes to normal growth and development and a higher intake is needed during pregnancy.5 The daily zinc requirement rises by almost 40% in pregnancy, based on the US Institute of Medicine (IOM) recommendations.2

The iodine needs are also significantly raised, with a 46% increase in demand during pregnancy than before conception, based on the IOM-recommendations. A sufficient iodine intake is important as it supports normal growth and cognitive development of the child.

Maternal calcium needs do not change compared to non-pregnant women in the same age group, as calcium uptake becomes more efficient during this period.7 However, even with this more efficient uptake, a sufficient calcium intake is still needed to support normal bone development of the infant as well as maternal bone maintenance.5 Evidence suggests that intakes above 500 mg/day are necessary to ensure sufficient calcium for the mother.6 

Vitamin A & B12

Although vitamin A and B12 are key vitamins in pregnancy, their requirements only marginally increase. Vitamin B12 plays a role in cell division and red blood cell formation.5  A  strong association is seen between maternal and infant plasma and vitamin B12-concentrations at delivery, illustrating the link between maternal vitamin B12-status and the infant’s stores after birth.7

Vitamin A has several functions and is, for example, needed for the normal functioning of the maternal immune system.5 However, too high an intake (IOM: retinol > 3 mg per day) may have adverse health effects on the fetus, which is why pregnant women are discouraged from eating products high in vitamin A, such as liver. 2,3,8

Folic acid, vitamin D and iron supplementation

Supplementation of some micronutrients is recommended because of their importance during pregnancy in combination with the potential risk of low dietary intakes of these micronutrients. Folic acid contributes to maternal tissue growth, iron to cognitive development, and vitamin D supports bone development.5 These nutrients are not always sufficiently available in a regular diet to ensure that the recommended daily intake is attained.

Pregnant women in the Netherlands are advised to use folic acid supplements (400 µg per day) in the first weeks of pregnancy, while in the United States folic acid supplements are only advised prepregnancy.3,8 A vitamin D-supplement of 10 µg/day is recommended in the Netherlands, while iron supplements are recommended in, for example, Malaysia and the United States (27 mg daily).1,3,8,9

Global differences and future research

The global differences in recommendations (as illustrated in table 1) may be attributed partially to cultural and dietary differences throughout the world. In addition, ongoing research adds to differences in interpretation of nutritional requirements. In 2010 the vitamin D-recommendation was subject of fierce debates in the US, with IOM recommending 15 µg/day, while the Endocrine Society advocated amounts of up to 50 µg/day in pregnancy.10 In some countries the maternal age (for example the United States) and stage of pregnancy (for example the Netherlands) is taken into account to refine nutrient recommendations, addressing insights in additional relevant factors influencing nutrient needs.2,3

In 2010 Berti et al. 11 from the European Micronutrient Recommendations Aligned (EURRECA) Network group concluded there is a need for more scientific data to refine existing recommendations. They plead for further study into the influence of maternal age and the role of socio-economic factors.  Additionally, they recommend research to define optimal levels for maternal and fetal health, reliable biomarkers and the most effective way and dosage to supply micronutrients, including appropriate timing in pregnancy. This should lead to more tailored recommendations for pregnant women.

References

  1. Recommended Nutrient Intakes (RNIs): Recommended Nutrient intakes for Malaysia. Ministry of Health, NCCFN. Petrujaya, 2005.
  2. Institute of Medicine. Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes, Vitamins. http://www.iom.edu/Activities/Nutrition/SummaryDRIs/DRI-Tables.aspx. Last updated: 12 September 2011. Accessed at 17 June 2013.
  3. Voedingscentrum Encyclopedie. www.voedingscentrum.nl. Accessed at 27 June 2013
  4. Health Promotion Board Singapore. Recommended Dietary Allowances. http://www.hpb.gov.sg/HOPPortal/programmes-article/2652. Last update: 12 Jan 2013. Accessed at 27 June 2013.
  5. European Commission. EU Register on nutrition and health claims. Last update: 12 June 2013. Accessed at 27 June 2013.
  6. Hacker AN, Fung EB, King JC. Role of calcium during pregnancy: maternal and fetal needs. Nutr Rev. 2012 Jul;70(7):397-409.
  7. National Institutes of Health. Office of dietary supplements. Dietary Supplement Fact Sheets. http://ods.od.nih.gov/factsheets Accessed at 27 June 2013.
  8. National Health Institute. Vitamins and nutrition in pregnancy. nhs.uk. Last update: 12 June 2013. Accessed at 27 June 2013.
  9. S. Department of Health and Human Services and U.S. Department of Agriculture. Dietary Guidelines for Americans, 2010. 7th Edition, Washington, DC: U.S Government Printing Office, January 2011.
  10. Bischoff-Ferrari HA. Vitamin D – Role in Pregnancy and Early Childhood. Ann Nutr Metab 2011;59:17–21
  11. Berti C et al. Critical issues in setting micronutrient recommendations for pregnant women: an insight. Matern Child Nutr. 2010 Oct;6 Suppl 2:5-22.