Maintaining an adequate body weight, physical activity, and the absence of addictions affect the fertility of women and men. Proper nutrition in the periconceptional period plays an important role in ensuring optimal conditions for fetal development and reduces the risk of complications resulting from deficiencies of specific nutrients. This is particularly important in the case of unplanned conception or very frequent pregnancies. Through health education on these factors, implemented from early childhood, it is possible to achieve optimal nutritional status in people of reproductive age and increase the chances of having healthy offspring. 

Meeting energy and nutrient requirements in full is one of the important factors determining the normal course of pregnancy. The best measure of adequate energy intake is maintaining the recommended pre-pregnancy body weight and an appropriate weight gain during pregnancy. Proper nutrition during pregnancy should therefore fully cover energy and all essential nutrients while avoiding excessive intake. 

Intrauterine undernutrition can predispose to metabolic abnormalities in extrauterine life; it may cause abnormal development of blood vessels, pancreatic β-cells, insulin resistance, impaired muscle development, and dysfunction of the liver, kidneys, and other organs. Developmental disorders in fetal life, manifesting as low birth weight, may cause increased risk of perinatal and early childhood mortality, greater susceptibility to infections, and increased predisposition in adulthood to type 2 diabetes, hypertension, dyslipidemia, and cardiovascular diseases. 

Excessive maternal nutrition is also unfavorable, as it may contribute to fetal macrosomia, pregnancy and delivery complications, and increased cardiovascular risk in the mother. High birth weight is often associated with overweight and increased risk of metabolic syndrome in adulthood. It is worth emphasizing that women who gain excessive weight during pregnancy more often develop gestational diabetes and, later in life, obesity and its complications.

The impact of pregnancy on energy expenditure changes by trimester and varies significantly among women depending on pre-pregnancy BMI and physical activity. This expenditure results primarily from increased energy needs of growing tissues, related to the growth of the fetus and placenta and the increased work of the maternal heart and lungs.

Standards for pregnant and lactating women account for increased energy demand in line with FAO/WHO/UNU recommendations. In 2020, new caloric requirements for pregnant women in Poland were developed. Unlike the previous ones, the current standards specify the additional energy needs in the first, second, and third trimesters as +85, +285, and +475 kcal/day, respectively. Earlier standards considered additional energy only in the second and third trimesters. 

The specified standards apply to women with normal pre-pregnancy body weight. In overweight women, additional energy needs during pregnancy are lower. The energy value of their diet should not promote excessive weight gain. In women underweight, additional energy needs may differ from those with normal weight. In such cases, individual consultations with a physician and dietitian are recommended. The latest guidelines do not specify exact energy needs for multiple pregnancies or for women nursing more than one child. Here too, consultation with a physician and dietitian is very important. 

A rational diet during pregnancy, besides providing adequate energy, should also include essential nutrients (proteins, fats, carbohydrates, minerals, and vitamins) in proper amounts and proportions.

The foundation of healthy eating during pregnancy should be variety and diversification of foods. Foods differ in composition and in their content of essential nutrients. There is no single product that covers 100% of needs for all nutrients in the right amounts and proportions. This principle helps avoid deficiencies: the more varied the diet, the lower the risk of deficits. It is recommended to include cereals, vegetables, fruits, milk and dairy products, and meat and its substitutes as sources of complete protein in the daily diet. Meals should be composed from all food groups, in appropriate proportions, and accompanied by fluids. 

List of selected fish and seafood recommended, acceptable, and not recommended in the diet of women planning pregnancy, pregnant women, breastfeeding women, and small children*

 

1 From time to time in limited amounts (max. 1 serving/week)

 * Based on recommendations of Polish scientific societies and opinions of EFSA, FAO/WHO, and FDA 

In the new recommendations (from 2020) for pregnant women, as in the case of energy, an additional amount of fat for the first trimester is provided and fat norms for the second trimester are updated. 

Table 2. Addendum to the reference intake standard for fat in pregnant and breastfeeding women

 

Table 3. Recommendations for adequate intake (AI) of omega-3 (n-3) and omega-6 (n-6) fatty acids in adult diets** 

 

* Adequate Intake (AI)—the level of nutrient intake established based on average consumption in a given group, used when there are insufficient data to establish an average requirement and adequate intake. 

** Based on recommendations of Polish scientific societies and opinions of EFSA and FAO 

A properly balanced diet should provide all essential nutrients, vitamins, and minerals. Due to significantly increased demands during pregnancy, meeting requirements may sometimes be difficult. Reasons include low protein content in the diet, an individual reduced ability to absorb and metabolize certain nutrients, and significant losses of labile nutrients during heat processing and storage. Therefore, to prevent deficiencies and their adverse health effects, breastfeeding women are additionally recommended to supplement individual nutrients with pharmaceutical preparations at strictly defined doses. Properly selected and appropriately used multivitamin-mineral supplementation increases the chance of a normal pregnancy course (reduced risk of preterm birth, low birth weight, and perinatal neonatal death). Nutrition surveys in Poland have shown widespread use of multicomponent preparations by pregnant women, among whom as many as 22% admitted to taking several products simultaneously, despite the lack of medical recommendations. Dietary supplements are easily accessible. They can be purchased over the counter (pharmacy, gas station, online stores), leading to the belief that they are harmless. Uncontrolled intake of multicomponent preparations carries a high risk of overdosing and interactions with chronically used drugs (e.g., antibiotics, cardiology drugs). For this reason, consultation before starting supplementation is recommended, taking into account the current diet, eating habits, and individual nutrient requirements. According to current knowledge, the greatest risks are associated with excessive intake of vitamin A, beta-carotene, calcium, copper, fluoride, iron, and zinc. 

Vegan and vegetarian diets may pose a dilemma for expectant mothers and caregivers. According to the Academy of Nutrition and Dietetics, “well-planned vegan and other types of vegetarian diets are appropriate for individuals at all stages of life, including pregnancy and lactation, infancy, childhood, adolescence, and for athletes.” A summary of a systematic review of 22 studies (13 on health effects in fetuses and mothers, 9 on nutrient deficiencies) was similar: “vegan and vegetarian diets can be considered safe during pregnancy, provided attention is paid to meeting vitamin and mineral requirements.” For this purpose, the care of a dietitian specializing in vegetarian diets is highly advisable. The key issue is assessing vitamin B12 status and adequate intake.

Basic dietary recommendations for pregnant women

Type of product	Recommended daily intake (number of servings)	Notes
cereal products	7–8	with every meal; preferably whole-grain products
dairy products	3–4	prefer unsweetened fermented milk drinks, low-fat cottage cheese, hard cheeses, and reduced-fat milk
high-protein products (meat, fish, eggs)	2–3	fish 2–3 times a week, including at least once fatty marine fish
vegetables	4–5	preferably raw*
fruits	2–3	preferably raw*
fats	2–3	prefer plant-based (oils, olive oil, soft margarines); as little animal fat as possible
fluids	2–2.5 l	70–80% as low-mineralized bottled water
* Freshly squeezed or puree juices without added sugar count as servings of vegetables or fruits, not as fluids to quench thirst.

Recommendations of the Polish Society of Gynecologists and Obstetricians regarding supplementation in pregnant women (selected issues) 

Iron

Given the adverse effects of both deficiency and excess iron on pregnancy and obstetric outcomes, and other possible causes of anemia in pregnancy besides iron deficiency, it is recommended to: 

1. check CBC and ferritin at the first obstetric visit, then CBC at weeks 15–20, 27–32, 33–37, and 38–39 of pregnancy (per the Standard of Care in Physiological Pregnancy—Regulation of the Minister of Health); 

2. use iron preparations before 16 weeks in women with iron-deficiency anemia (Hb < 11 g/dl and low ferritin); 

3. allow supplementation up to 30 mg/day in women without anemia but with ferritin < 60 μg/l after 16 weeks; 

4. in treating iron-deficiency anemia—use low oral doses for a longer time; if there is no response, switch to a preparation with proven higher bioavailability or increase the dose and continue monitoring; 

5. if there is no response to high therapeutic oral doses or Hb < 7 g/dl, consider transfusing packed red blood cells.

Docosahexaenoic acid (DHA)

Based on current knowledge of DHA effects on pregnancy and obstetric outcomes, the following are recommended: 

1. supplementation of at least 200 mg DHA in all pregnant women; 

2. in women consuming little fish before and during pregnancy, consider higher doses of DHA; 

3. in women at risk of preterm delivery, DHA at 1000 mg/day.

Vitamin D

In light of current knowledge, it is recommended: 

1. during pregnancy and lactation in women without risk factors for deficiency and with normal BMI, supplement 1500–2000 IU vitamin D per day; 

2. optimal (suggested) management is to adjust the vitamin D dose to serum levels; 

3. in women with BMI > 30 kg/m², consider doses up to 4000 IU/day.

Iodine

Based on the latest research, it is recommended: 

1. iodine supplementation in all pregnant women without a history of thyroid disease at 150–200 μg/day; 

2. in women with thyroid disease, supplementation should be guided by thyroid hormone and antithyroid antibody levels.

Folic acid 

According to current knowledge, it is recommended: 

1. all women of reproductive age should take 0.4 mg/day of folic acid as a supplement, in addition to a natural folate-rich diet; 

2. in the first trimester (to week 12), 0.4–0.8 mg/day; 

3. after week 12 and during lactation, in women without additional risk factors, 0.6–0.8 mg/day; 

4. in patients with a history of NTD in a previous pregnancy, 4 mg/day starting at least 4 weeks before conception and through the first 12 weeks, then reduce the dose as in the general population; 

5. in women at increased risk of folate deficiency and neural tube defects, i.e.: 

• with type I or II diabetes prior to pregnancy, 

• using during or before pregnancy antiepileptics, methotrexate, cholestyramine, metformin, sulfasalazine, 

• using substances of abuse

• with kidney or liver failure, 

• with BMI > 30, 

• after bariatric surgery or with gastrointestinal diseases causing malabsorption (Crohn’s disease, ulcerative colitis, celiac disease)