Diet of pregnant women

Specific Recommendations: First trimester

Energy supply:

The increased demand for energy and nutrients during pregnancy is related to both the development of the fetus, as well as the placenta and maternal tissues. The increasing body weight of the mother-to-be also increases the level of basal metabolism, requiring a gradual increase in kcal intake. 

During the first weeks after conception, the additional energy expenditure is small. An increase occurs towards the end of the first trimester.

According to estimates, the increase in energy requirements during the first trimester of pregnancy is about 150 kilocalories per day. However, if a woman has an appropriate weight before pregnancy - she is not underweight - there is no need to increase her energy intake during the first trimester. In order to determine the daily energy requirements of a pregnant woman, factors such as age, body weight before pregnancy, work-related lifestyle elements and physical exercise must be taken into account. 

Both underweight and obesity before and during pregnancy can be associated with many complications. It is therefore important to monitor a pregnant woman's appropriate weight gain in relation to her pre-pregnancy BMI (body mass index) value. 

Total weight gain throughout pregnancy should be for: 

- underweight (BMI< 18,) 12.5- 18kg; 
- normal weight (BMI= 18.5-24.9) 11.5-16kg; 
- overweight (BMI= 25-29.9); 7-11.5kg;
- obese (BMI ≥ 30) 5-9 kg 
During the first trimester of pregnancy, the optimal weight gain should be between 0.5 and 2 kg.

Nutrients:

For protein, according to Polish standards, it is recommended that pregnant women consume about 1.2g per kilogram of body weight of this component per day. The quality of protein is important: approximately 60% should be wholesome protein, i.e. of animal origin. Its recommended sources include milk and dairy products (very important also because they are a source of calcium - it is recommended that pregnant women consume 3-4 glasses of milk or fermented dairy products daily), fish, eggs and lean meats. It is important to avoid raw meat (e.g. tartare), raw fish (e.g. sushi), raw eggs, mouldy cheese and unpasteurised milk. These products can be a potential source of infection with pathogenic microorganisms that pose a threat to the developing baby. The remaining 40% of protein should be of plant origin. It can be provided in the daily diet with products such as pulses (if they are well tolerated by the future mother). 

The proportion of fats in the daily diet of pregnant women should cover 20-35% of the energy requirements. It is important that saturated fatty acids are consumed in the smallest amount possible, but unsaturated fatty acids should be chosen as often as possible. During pregnancy, the body's requirement for unsaturated fatty acids increases by up to 50%. They must be supplied with food. The main sources of unsaturated fatty acids are vegetable oils such as rapeseed oil, olive oil and sunflower oil. In addition, fatty marine fish, nuts and seeds are also sources of these acids.  Particularly important during pregnancy are omega-3 unsaturated fatty acids. These include ALA, the consumption of which should amount to at least 0.5% of the daily energy value of a pregnant woman's diet. In addition, DHA and EPA fatty acids, whose recommended intake is 100-200mg/day and 250mg/day respectively. The appropriate amount of these acids is necessary, among others, for the proper development of the child's brain, the proper functioning of neurons.  Sources of omega-3 fatty acids are oily sea fish (it is recommended that pregnant women eat two portions of oily sea fish a week), rapeseed oil, flaxseed, walnuts.  

During pregnancy it is recommended to limit animal fats, which are a source of saturated fatty acids. They increase the level of cholesterol in the blood, thus contributing to the development of atherosclerosis. You should also avoid products such as hard margarine, fast food, powdered sauces and soups, sweets, as they contain harmful trans fatty acids. 

Carbohydrates in the diet of pregnant women should provide 55-60% of daily energy needs. The best choice will be complex carbohydrates, the source of which may be: wholemeal flour; wheat, buckwheat, spelt, wholemeal bread, oatmeal, rice, groats, pasta, potatoes. 

It is recommended to choose wholemeal products, because they contain a much higher content of vitamins and minerals than purified products (e.g. light bread). 

Simple sugars should be limited, their share should not exceed 10% of the daily energy value of the diet. 

It is also important to have an adequate supply of fiber (20-40 g per day). Its sources are the aforementioned cereal products, vegetables and fruits. Apart from being a source of fibre, vegetables and fruit provide valuable vitamins and minerals. The diet of a pregnant woman in the first trimester should include at least 400g of vegetables and 300g of fruit daily. 

Hydration:

During pregnancy, due to the increase in circulating blood volume, as well as the development of fetal tissues and the increasing weight of a woman's organs, the need for fluids increases. From the very beginning of pregnancy, water is an essential part of the baby's proper development. Water enters the fetus from the mother's circulation through the placenta. Approximately 450 ml of water are exchanged through the placenta per hour.  Many discomforts associated with the first trimester (e.g., nausea, constipation, vomiting, dry skin) can be reduced with proper hydration. The recommended fluid intake during pregnancy is an individual matter and is related to a number of factors (ambient temperature, degree of humidity, weight of the pregnant woman and the activity she undertakes).  It is generally accepted that the average fluid intake during pregnancy is about 2-2.5 litres per day. Sweetened, colourful and energizing drinks should be excluded from the diet of a pregnant woman. Under no circumstances should a pregnant woman consume alcoholic beverages, even in small quantities. It is especially recommended to drink water, which should constitute the majority of the consumed beverages. It is worth choosing bottled spring water or low-mineralised mineral water. The rest can be covered by drinking fruit teas, herbal teas allowed for pregnant women, vegetable or fruit juices without added sugar. Some of the recommended amount of fluids is also supplemented with the consumption of milk, dairy products and soups. 

Mandatory supplementation:*

Folic acid: 0.4mg/day

Iodine: 200 µg/day

Vitamin D3: 2000IU/day

*Further details in the article

Dietary recommendations in subsequent trimesters are largely the same as those in the first trimester. Differences and additional recommendations are detailed below. 

Additional recommendations: second trimester 

Energy supply:

According to current Polish nutrition standards, the energy value of a pregnant woman's daily ration during the second trimester should be increased by 360 kcal per day. 

In the case of a gradual increase in body weight during the second trimester, it is recommended that the normal weekly increase should be approx:

0.5-0.6 kg/week if underweight
0.4-0.5 kg/week for normal weight
0.2- 0.3 kg/week if overweight or obese
Nutrients:

The protein supply is analogous as during the first trimester. However, the supply of fats has changed and should be increased by 8-14 grams per day. Due to the increase in calories the carbohydrate intake should also be increased so that it accounts for 55-60% of the current kcal intake. It is also advisable to increase the supply of vegetables and fruits by an additional 100g.

Mandatory supplementation:*

Iodine: 200 µg/day

Vitamin D3: 2000IU/day

*Further details in the article

Additional recommendations: 3rd trimester

Energy supply:

During the third trimester, the additional kilocalorie intake should be 475 kcal per day. 

The normal weekly weight gains are analogous to those shown in the 2nd trimester. 

Nutrients:

Protein supply is analogous as during the first trimester (1.2g/kg b.w./d). What changes is the fat intake, which should be increased by 11-18 grams per day. Due to the increase in calories, the carbohydrate intake should also be increased to 55-60% of the current kcal intake. 

Mandatory supplementation:*

Iodine: 200 µg/day

Vitamin D3: 2000IU/day

*Further details in the article

Supplements during pregnancy

During pregnancy, an adequate supply of vitamins and minerals is very important. It is important that the daily diet of a pregnant woman is varied and consists of a variety of food products. This makes it easier to avoid nutritional deficiencies, to which future mothers are particularly prone. In case of insufficient supply of folates, vitamin D, iodine, iron, it may lead to the development of disorders in the developing child. Each supplementation should be introduced after prior consultation with a doctor. 

All women planning pregnancy should implement folic acid supplementation, at least six weeks before conception, due to the risk of neural tube defects if this component is deficient. Folic acid supplementation of 0.4mg/d should then be continued for the first 12 weeks of pregnancy. In the case of women with a family history of neural tube defects and women on antiepileptic drugs, a higher dose of folic acid should be used. According to the recommendations of the Polish Gynaecological Society, the dose of folic acid should also be increased in women with obesity, hyperhomocysteinemia and during treatment of megaloblastic anaemia. 

The need for iodine also increases during pregnancy. This is due, among other things, to the demands of the developing child, an increase in the activity of deiodinases, and loss of iodine by the kidneys. Insufficient iodine supply can contribute to the risk of mental retardation in children.  An increased need for iodine is already observed in the first trimester. The recommended daily dose of iodine for women who are planning pregnancy, pregnant or breastfeeding is 200 μg/day. 

Vitamin D3 also plays a very important role. The supplementation dose of vitamin D3 should be determined individually by a doctor after determination of 25(OH)D concentration in blood. Usual doses are 800-2000 IU/day, depending, among others, on body weight, from September to April or for all months if it is not possible to ensure effective skin synthesis during the summer months. According to the recommendation of the Polish Gynecological Society, vitamin D3 should be supplemented in both women planning pregnancy and pregnant women and during lactation at a dose of 2000IU/day on average. 

The iron requirement in the diet of pregnant women increases significantly to 27 mg. Therefore, pregnant women are particularly at risk for iron deficiency anemia. For women diagnosed with anemia prior to planned pregnancy, oral iron supplementation should be conducted prior to conception and again after the 8th week of pregnancy. If a pregnant woman is diagnosed with anemia, it is important to quickly intervene with a physician and introduce supplementation with iron preparations after the completion of the 8th week of pregnancy at a dose starting at 30mg/day and increasing the dose to 60-120mg if various degrees of anemia are confirmed. 

Due to the very important benefits of omega-3 fatty acids, especially DHA (the main source is oily sea fish), it is very important to provide them with a diet. If a pregnant woman does not consume fish or other sources of DHA, it is recommended to take at least 600mg of DHA daily. On the other hand, in case of high risk of preterm birth, it can be as much as 1000mg/day of DHA. 

Supplementation of both vitamins and minerals should be individualized, always consulted with a doctor, and its planning should take into account changes depending on pregnant woman's nutritional habits and membership of given risk groups. According to the current state of knowledge, folic acid, iodine and vitamin D3 supplementation by pregnant women is indisputable in view of the confirmed risk of deficiency of these components in the population. On the other hand ingredients such as iron, DHA or e.g. magnesium and others should be supplemented depending on the occurrence and degree of deficiencies or specific risk of their occurrence.

To sum up: a well-balanced, individualised diet is essential both during pregnancy planning and during pregnancy. It is important to remember that pregnancy is by no means a time for dieting or "eating for two". Adequate calorie, macronutrient, vitamin and mineral supply from a variety of food groups is the safest and most enjoyable way to eat during this special time. 

Source:

• Jarosz M. Praktyczny podręcznik dietetyki. Szostak-Węgierek D. Ciąża.Warszawa: Instytut Żywności i Żywienia; 2010: 71–77. 
• Karowicz-Bilińska A., Nowak-Markwitz E., Opala T. i wsp.: Rekomendacje Polskiego Towarzystwa Ginekologicznego w zakresie stosowania  witamin i mikroelementów u kobiet planujących ciążę, ciężarnych i karmiących. Ginekol Pol. 2014,85(5), 395-399.
• Makowska-Donajska M., Hirnle L.: Suplementacja witamin i składników mineralnych podczas ciąży. Ginekologia i Perinatologia Praktyczna 2017;  4 (2), 166–172.
• Wendołowicz A., Stefańska E., Ostrowska L.: Żywienie kobiet w okresie ciąży. Med. Og Nauk Zdr. 2014; 21(3): 341–345.