Important Nutrients During Pregnancy

Folic Acid

Pregnant women should take a daily supplement containing 400µg of folic acid for at least 4 weeks before pregnancy and for the first 12 weeks of pregnancy1.

This B vitamin can reduce the risk of neural tube defects (NTDs), such as Spina Bifida, in the newborn. Pregnant women should also consume a diet rich in the natural form of folic acid, called folate. Dietary sources of folate include fruits such as oranges, green leafy vegetables, and foods fortified with folic acid such as breakfast cereals.

Women who have had an infant with an NTD should be prescribed a daily supplement containing 4,000?g of folic acid at least 4 weeks prior to conception and for the first 16weeks of pregnancy to help prevent recurrence1.


Iron is important for the production of red blood cells. Requirements for iron increase throughout pregnancy due to the increasing growth of the foetus, uterus, increased blood cell count, and expected blood loss during delivery. A pregnant woman requires 15µg iron per day2.

Iron deficiency anaemia (IDA) is associated with poor pregnancy outcomes such as:

  • Pre-term birth
  • Low birth weight
  • Maternal mortality
  • Pre-eclampsia

Maternal morbidity (fatigue, increased infections, poor resistance to cold)

Maternal iron deficiency is also a risk factor for IDA in the infant in the first year of life3 and impaired cognitive function in the offspring4. Irish research shows that on a population level, a significant proportion of women of child-bearing age are not reaching their daily requirements for iron, therefore they may be entering pregnancy with suboptimal levels5.

Red meat is an excellent source of iron. Other good sources include poultry, fish, baked beans, eggs, dark green leafy vegetables (e.g. spinach, broccoli), raisins and fortified milks and breakfast cereals (check the labels). To help the body absorb more iron from non-meat sources, combine a vitamin C rich food (e.g. citrus fruits, tomatoes, berries, peppers) in the same meal, e.g. pack omelettes with cherry tomatoes and peppers, or have a glass of pure fruit juice with a bowl of iron-fortified breakfast cereal.


Calcium is important for a baby’s developing bones and teeth. Pregnancy-induced adaptions to maternal calcium homeostasis, such as up-regulation of intestinal calcium absorption, provides the extra calcium required for foetal growth. Intestinal calcium absorption more than doubles during pregnancy to meet this increased need6.

Maternal Calcium requirements do not increase during pregnancy – 1000mg/d Females >18yrs, 1300mg/d Females 15-18yrs1.

Dairy foods are an excellent source of calcium. Low fat dairy products are best, as they contain the same amount of calcium but less fat than full fat varieties. Unpasteurised dairy products including mould-ripened cheese and all soft cheeses (both pasteurised and unpasteurised) should be avoided during pregnancy to reduce the risk of exposure to the bacteria listeria that can be harmful to the baby. Other sources of calcium include fortified breakfast cereals, breads and orange juice (check the labels). Dark green leafy vegetables also contain a small amount of calcium. If a pregnant mother is using soya alternative products, they should use varieties that contain added calcium.

Vitamin D

Vitamin D is a fat soluble vitamin that aids the absorption of calcium in the body. Endogenous vitamin D production occurs via the action of ultraviolet B (UVB) rays in sunlight on the skin. However, due to Ireland’s northerly latitude, little UVB light reaches the earth’s surface and so reduces the production of vitamin D3. Therefore we require vitamin D-rich foods in our daily diets to reach our vitamin D requirements.

There are unfortunately very few dietary sources of vitamin D. Good sources include oily fish (e.g. salmon, trout, sardines, herring, and mackerel) and egg yolks. Also some brands of breakfast cereals, margarines and milks are fortified with vitamin D (check the labels).

25-hydroxy vitamin D (25(OH)D) is the storage form of vitamin D. 25(OH)D crosses the placenta and cord blood concentrations are equal to or up to 20% lower than maternal levels7. Therefore, for an infant to be born with sufficient levels of Vitamin D it is crucial that the mother is vitamin D sufficient.

SLÁN 2007 showed that the average Vitamin D intake of Irish women of reproductive age was 3.5µg/day – well below the recommended intake of 10µg/day8. More recently the National Adult Nutrition Survey 2011 reported that the average vitamin D intake in female adults in Ireland (18-64 years) was 3.9ug/day and this reduced to 3.1ug/day in 18-35 year old women.9 Holmes V et al. (2009) showed that in Northern Ireland 96% (12 and 20 weeks gestation) and 75% (35 weeks gestation) of pregnant women were vitamin D insufficient (25(OH)D ,<50nmol/l)10.

The HSE and Food Safety Authority of Ireland (FSAI) recommended that all pregnant women in Ireland take a daily 5µg Vitamin D supplement as well as consuming vitamin D rich foods daily.

Omega-3 Fatty Acids

Omega-3 fatty acids are important for the baby’s brain and eye development. Omega fatty acids are essential fats that can only be sourced through the diet. Oily fish, such as herring, mackerel, salmon, sardines or trout are excellent sources of omega-3. Other sources include white fish such as cod and whiting (but in much lower levels) some plant/nut oils such as canola (rapeseed), linseed, flaxseed and walnut oil, some nuts and seeds for example sesame, flaxseed and walnuts. A pregnant mother should aim to eat oily fish 1-2 times per week1.

EPA and DHA are essential fatty acids derived from food sources of ?-linolenic acid (omega-3). In pregnancy, only 9% of ?-linolenic acid is converted to EPA and DHA11. Even high intakes of ?-linolenic acid have been shown to fail to increase maternal blood levels of EPA and DHA12. Therefore, adequate dietary intakes of these two omega-3 fatty acids depend on consumption of food sources and use of food supplements.

EPA and DHA are selectively transported through the placenta to the growing foetus. Maternal stores of EPA and DHA become depleted, especially in the 3rd trimester, during pregnancy due to foetal uptake. Preterm infants may therefore be born with low stores of EPA and DHA3.

Eicosanoid derivatives of EPA reduce inflammation and blood clotting. DHA forms an integral part of the phospholipid membranes in the central nervous system. Optimal functioning of the CNS has been shown to be linked with DHA availability during critical periods of growth during pregnancy when the CNS tissues are being formed14.

Research shows that women who consume sufficient levels of EPA and DHA during pregnancy tend to deliver babies with higher levels of intelligence, better vision, and a more mature CNS functioning15-17




  1. Food Safety Authority of Ireland (FSAI). (2012). Scientific Recommendations for a National Infant Feeding Policy, 2nd Edition
  2. Food Safety Authority of Ireland (FSAI). 1999. Recommended Dietary Allowances for Ireland
  3. Freeman VE et al. (1998). A longitudinal study of iron status in children at 12, 24 and 36 months. Public Health Nutrition. 1: 93-100.
  4. Tamura T et al. (2002). Cord Serum Ferritin Concentrations and Mental and Psychomotor Development of Children at Five Years of Age. Obstetrics: Newborn Medicine. 57(8): 494-495
  5. Morgan K et al. (2008). SLAN 2007: Survey of Lifestyle, Attitudes & Nutrition in Ireland: Main Report
  6. Kovacs CS. (2011). Calcium and Bone Metabolism Disorders during Pregnancy and Lactation. Endocrinol Metab Clin N Am.40:795–826
  7. Kovacs CS et al. (2008). Vitamin D in pregnancy and lactation: maternal, fetal, and neonatal outcomes from human and animal studies. Am J Clin Nutr. 88 (2): 520S-528S
  8. Morgan K et al. (2008). SLAN 2007: Survey of Lifestyle, Attitudes & Nutrition in Ireland: Main Report.
  9. The National Adult Nutrition Survey 2011. Available online at
  10. Holmes V et al. Vitamin D deficiency and insufficiency in pregnant women: a longitudinal study. BJN: 102. 876–881
  11. Williams CM et al. 2006. Long-chain n-3 PUFA: Plant v marine sources. Proc Nutr Soc. 65:42-50
  12. Position of the American Dietetic Association and Dietitians of Canada. (2007). Dietary fatty acids. J AM Diet Assoc. 107: 1599-1611
  13. Makrides M. (2008). Outcomes for mothers and their babies: Do n-3 fatty acids make a difference? J Sam Diet Assoc. 108: 1622-26
  14. Alessandri JM et al. (2004). Polyunsaturated fatty acids in the central nervous system: evolution of concepts and nutritional implications throughout life. Reprod Nutr Dev. 44: 509-38
  15. Szajewska H et al. 2006. Effect of n-3 long chain polyunsaturated fatty acid supplementation of women with low-risk pregnancies on pregnancy outcomes and growth measures at birth: A meta-analysis of randomized controlled trials. Am J Clin Nutr. 44:509-38
  16. Hellend IB et al. (2008). Effect of supplementing pregnant and lactating mothers with n-3 very-long-chain fatty acids on children’s IQ and body mass index at 7 years of age, Pediatrics. 122:e472-9
  17. Judge MP et al. 2007. Maternal consumption of DHA-containing functional food during pregnancy : Benefit for infant performance on problem solving but not recognition memory tasks at age 9 mo. Am J Clin Nutr. 85: 1572-7

Food pyramid image taken from the Food Safety Authority of Ireland (FSAI). (2012). Healthy eating and active living for adults, teenagers and children over 5 years. Accessed September 2016 at: