Pregnancy is typically a time when many women are motivated to make positive dietary and lifestyle changes, therefore healthcare professionals should use this critical time to encourage long-term dietary and lifestyle changes. A healthy, balanced diet in pregnancy can have profound and lifelong effects on the infant’s health, with certain key nutrients being particularly important to help protect a mother’s health and to promote the healthy development of the infant. In addition, regular exercise both during and after pregnancy can help women to regain their strength once they have given birth.

Diet in pregnancy

Having a healthy balanced diet is important during all stages of the lifecycle but at no other stage does nutrition have such profound life-long effects than during the First 1000 days of life. The First 1000 Days represents the time period from conception to a child’s 2nd birthday, and optimal nutrition during this timeframe has the ability to reduce a child’s risk of developing chronic adulthood diseases including Type 2 diabetes, obesity, hypertension, stroke, and coronary heart disease (CHD)1.

Optimum nutrition can be achieved during pregnancy by following the general population healthy eating guidelines as set by Food Safety Authority of Ireland2. In other words, there is no special ‘pregnancy diet’.

Pregnancy is typically a time when many women are motivated to make positive dietary and lifestyle changes, therefore healthcare professionals should use this critical time to encourage long-term dietary changes.

Certain key nutrients are particularly important to help protect a mother’s health and to promote the healthy development of the infant.


It is important that pregnant women have an adequate energy intake to support the growth and development of the foetus and so that the mother herself maintains a healthy body weight throughout pregnancy. Pregnant women are not ‘eating for two’ and excessive energy intakes should be avoided. It is also important that pregnant women do not undergo calorie restriction diets during pregnancy as this could have a life-long, negative impact on their infant’s growth and health. 

An average female adult requires about 2000 calories per day. The following table shows the additional calories required during pregnancy by trimster3.


Trimester of pregnancyAdditional Calories required daily (kcal/d)
Trimester 10
Trimester 2350
Trimester 3500

Nutritious snacks such as fruit, low-fat plain yogurt topped with berries, vegetable sticks and hummus, wholemeal toast and cheddar cheese, or crackers/crispbread and tinned salmon can meet the modest increase in calories during trimester 2 and trimester 3.

Long Chain Omega-3 Polyunsaturated Fatty Acids

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are two important long chain omega-3 polyunsaturated fatty acids that that play an important role in slowing down blood clot formation in the pregnant woman and also have a protective effect against heart disease in the mother. DHA is also important for the development of the foetal brain, retinas in the eyes, and nervous system4.  

Pregnant women should be encouraged to consume oily fish up to once per week to to provide EPA and DHA2. Oily fish includes salmon, trout, herring, mackerel, and tuna. Due to the mercury content of tuna, pregnant women should limit their intake of tuna to one fresh tuna steak (150g) per week or two 240g cans of tinned tuna per week2.

Vitamin D

Vitamin D is required for good bone health, both for mother and the developing foetus. There are only a few natural dietary sources of vitamin D including oily fish, eggs, some fortified cereals and fortified milks. Endogenous vitamin D intake is limited in the Irish population due to Ireland being a lower latitude country.  

Consuming oily fish once a week can contribute to a pregnant woman’s dietary intake of vitamin D, as well as consuming foods fortified with vitamin D such as fortified breakfast cereals and fortified milks. While liver is a good source of vitamin D it should not be consumed during pregnancy due to the high vitamin A content.  

The HSE5 and FSAI3 also recommend taking a daily vitamin D supplement of 5µg (200 IU) during pregnancy.


Pregnant women require 15mg iron per day7. The developing foetus requires a large amount of red blood cells to provide sufficient oxygen for growth. Requirements for iron increase throughout pregnancy due to the increasing growth of the foetus, uterus, increased blood cell count, and expected blood loss during delivery6. If a mother’s iron status is too low, the placenta will be more efficient at removing iron from the mother’s circulation. Increased iron requirements during pregnancy is also helped by the cessation of menstruation. 

Natural maternal adaptions that occur during pregnancy allow for the mother to better absorb iron from the diet, however it is still of utmost importance that iron-rich foods are included in the pregnant woman’s daily diet. ‘Haem iron’ from animal food sources (particularly red meat) is the most bio-available form of iron. ‘Non-haem’ iron is not as bioavailable and requires vitamin C to aid its absorption in the body. Non-haem iron sources include green leafy vegetables, pulses (peas, beans, and lentils), and foods fortified with iron such as some breakfast cereals. While liver is a good source of haem iron it should not be recommended during pregnancy due to the high vitamin A content.

Pregnant women can find it difficult to meet their iron requirements from diet alone, and in such cases a supplement may be needed7. However, women can experience uncomfortable gastrointestinal side effects such as constipation when taking iron supplements. The healthcare professional leading the care of the pregnancy should advise accordingly.

Folic Acid

In order to prevent neural tube defects, Irish policy recommends that women consume a daily 400µg folic acid supplement for a minimum of 12 weeks pre-conception, and until the 12th week of pregnancy in combination with a folate-rich diet7. If the mother has previously had an infant with a neural tube defect, a supplement containing 4000µg of folic acid per day is recommended to help prevent recurrence7.


Calcium is important for good bone health for the mother and developing foetus. 

Pregnant adult women require 1000mg calcium per day, with pregnant teenage girls requiring 1300mg per day7.

To achieve an intake of 1000mg calcium per day, pregnant women are advised to consume 3 portions of dairy products everyday. In general, pregnant women should be able to obtain their calcium requirements via diet alone, however, if a mother does not like milk or milk-based products, or is vegan or lactose intolerant then a calcium supplement may be advised by their healthcare professional7.

  1. Godfrey KM & Barker D. (2000). Fetal nutrition and  adult disease. Am J Clin Nutr. 71(suppl):1344S-52S.
  2. Food Safety Authority of Ireland (2019). Healthy eating, food safety and food legislation. A guide supporting the Health Ireland food pyramid.
  3. Food Safety Authority of Ireland (2012). Scientific Recommendations for a National Infant Feeding Policy, 2nd Edition.
  4. 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.
  5. Health Services Executive (2010). Policy on Vitamin D Supplementation for Infants in Ireland (
  6. Dewey KG & Chaparro CM (2007). Session 4:Mineral metabolism and body composition iron status of breast-fed infants. Proc Nutr Soc. 66(3):412-22.
  7. Food Safety Authority of Ireland (2012). Best Practice for Infant Feeding in Ireland.

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