For a long time, scientists have been making efforts to determine the influence of environmental and genetic factors on the incidence rate of the twenty-first century civilisation diseases, which is also extremely significant in the context of gynaecology and obstetrics. A significant fact is that in these areas, any pro-health educational activities and methods of passing on this knowledge are essential in disease prevention. For example, the method of passing on the knowledge on dietary factors and physical activity in prevention activities related to obesity and gestational diabetes are obligatory in health promotion. An appropriate lifestyle is important in prophylaxis, therapy, and as a complement to pharmacological treatment, and therefore should be taken into consideration in health-promoting educational activities [1, 2, 3, 4, 5, 6].

Aside from the prevention of illness, restoration of the sick and rehabilitation, promotion of health is one of the four major pillars of medicine. The World Health Organisation (WHO) defines health as “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity”. Health is a process of mutual conditions in the body-environment relationship that in the event of a lack of disease, maintain the equilibrium between the body and the environment. Health is the ability of a body to adapt to the environment.

Diet related issues play a significant role in health promoting activities, with diabetes prevention a real issue in this respect.

Diabetes has been considered a global epidemic, and poses a serious challenge in obstetrics. The World Health Organisation (WHO) estimates that the total number of people with diabetes will reach 522 million worldwide and 3.42 million in Poland by 2030. In women, the current estimate of type 1 diabetes is 2–3% and type 2 nearly 6%.

It should be strongly emphasised that six months prior to conception, women with diabetes need to plan the pregnancy to meet applicable standards in order to normalise carbohydrate levels.

Normal pregnancy involves a variety of hormonal and metabolic changes in a woman’s body aiming at providing building and energy substrates for foetal development [7], and the major nutrient is glucose, transported across the placenta by facilitated diffusion. Around the 9th week of pregnancy the pancreas of the fetus senses insulin, and around the 20th week $\beta$-cells secrete insulin in response to the increased level of glucose in the fetus. Prolactin and progesterone are responsible for changes in carbohydrate metabolism, and raise the level of blood glucose (insulin-antagonist effect), while placental lactogen regulates appetite and weight gain during pregnancy.

The first trimester is dominated by an anabolic state, where mainly fats are accumulated. The second half of pregnancy is a catabolic state, in which deposits of energy substances are released to cover the increased demand for energy for the fetus and placenta. In addition, maternal insulin resistance develops, where a rise in the level of progesterone causes an increase in glucotransporter 4 (GLUT–4) expression and inhibits glucose transport into adipose tissue and skeletal muscles [7, 8].

At the end of the pregnancy, increased concentrations of tumour necrosis factor (TNF–$\alpha$) are secreted from the placenta and adipose tissue. TNF–$\alpha$ decreases skeletal muscle glucose uptake, and by lowering concentrations of adiponectin it leads to post-meal hyperglycaemia [9]. Increased insulin secretion compensates for insulin resistance as the consequence of the increased expression of prolactin receptors in the pancreas, binding the placental lactogen. Lactotrophic hormones stimulate multiplication of $\beta$-cells, contributing to the expression of genes for insulin and glucose-dependent insulin secretion. At the end of the pregnancy, the demand for glucose is 6 mg/min/kg BW.

It needs to be strongly emphasised that the first step for pregnant women suffering from gestational diabetes involves introducing a balanced diabetic diet, which is often sufficient to balance blood sugar levels and to avoid needing insulin therapy. It should be borne in mind that the goal of a diet in gestational diabetes is not to lose weight, but to achieve the appropriate level of blood glucose concentration and avoid complications in both the mother and fetus [10, 11, 12, 13, 14, 15]:

• BMI—weight in kilograms divided by height in meters squared:

$\to$the average daily calorie intake for a pregnant woman is about 35 kcal/1 kg (1500–2400 kcal/day) at normal body weight before pregnancy;

$\to$25–30 kcal/1 kg for an overweight pregnant woman.

• A diet for a pregnant woman based on 6–7 meals a day in carbohydrate exchanges (CE);

$\to$Breakfast I—20% of the daily energy requirement—4 CE

$\to$Breakfast II—10% of the daily energy requirement—2 CE

$\to$Lunch—10% of the daily energy requirement—2 CE

$\to$Teatime—10% of the daily energy requirement—2 CE

$\to$Dinner I—25% of the daily energy requirement—4 CE

$\to$Dinner II—10% of the daily energy requirement—2 CE

An important element in pro-health education that is essential for positive treatment outcomes is to teach patients to count carbohydrates through an exchange system, which facilitates appropriate metabolic compensation and thus prevents later complications of diabetes that lead to chronic hyperglycaemia. It is not possible to dose the right amount of insulin without counting carbohydrates in meals [16, 17].

• Reducing total carbohydrate content to around 40–50% (ca. 180 g) of all the calories in the diet.

$\to$Recommended consumption of low glycaemic index products (50%), sugars reduced to a minimum.

$\to$Fructose should not substitute saccharose.

• Fibre—25–50 g or 15–25 g/1000 kcal, particularly water-soluble fractions (beta-glucans and pectins), and reducing fructose to 50 g.

• Daily consumption of cereal products rich in complex carbohydrates, proteins, iron, vitamin B, niacin, zinc, magnesium and fibre.

• Fruit and vegetables—rich in vitamin C, mineral components, beta-carotene and fibre. Potassium lowers blood pressure, while fibre prevents constipation, improves glucose tolerance, lowers cholesterol levels, and regulates the function of the gastrointestinal tract.

• Reducing consumption of sweets and sugar to prevent tooth decay and maintain normal body weight.

• Carbohydrate exchange (CE)—the amount of a product in grams that contains 10 g of carbohydrates assimilated by the body (e.g., 1 slice of bread contains 2 CE, which is equivalent to 20 g of sugar) [18].

• Fats—20–30% of energy in a 24 h diabetic diet;

$\to$Reducing saturated fatty acids to less than 10% of total energy intake.

$\to$Reducing mono-unsaturated fats (sesame and rapeseed oil, olive oil and nuts) to less than 10–15% of total energy intake;

$\to$Reducing polyunsaturated fats to 6–10% of the caloric content, e.g., 1–2% of Omega-3 acids and 5–8% of Omega-6 acids (sea fish, soya, corn, sunflower, saffron);

$\to$Cholesterol level below 300 mg/dL, or for patients with too high LDL fraction to below 200 mg/dL (20 g of saturated fatty acids, and 2 g of trans-isomers);

$\to$Bread with a thin layer of butter to prevent high cholesterol;

• Proteins as building blocks of the body;

$\to$Daily protein content—30%

$\to$Maintaining a daily 50/50 proportion of animal protein to vegetable protein

$\to$Daily intake of protein—1.3 g/kg BW/day [9]

$\to$Drinking 4 glasses of milk a day

$\to$Meat as a source of protein, vitamin B2, iron and niacin, should be consumed in moderation

$\to$Oily fish—2–3 times a week as a replacement for meat

• Folic acid supplementation—400 $\mu$g a day to prevent neural tube defects

• As pregnant women suffering from diabetes or taking insulin can experience a magnesium deficiency, they should take magnesium supplements or consume more products containing magnesium

• Daily intake of salt from different sources should be reduced to 8 g.

Glycaemic index (GI) measures the extent to which a specific food raises blood glucose. It is expressed as a percentage, e.g., an apple has a glycaemic index of 39%, which means that after eating an apple the rate of glucose increase in the blood will be 39% of that observed after eating pure glucose.

Glycaemic index depends on a variety of factors, e.g., the method of food preparation. The more minced or overcooked the product, the higher the glycaemic index. Cooking or other heating increases the glycaemic index by breaking down the starch in the food. Proteins and fats reduce GI—fat inhibits stomach emptying and makes digestion and absorption of carbohydrates less effective. Protein lowers post-meal blood glucose levels by affecting the cells secreting intestinal hormones and insulin. Ripe fruit has a higher glycaemic index as starch is decomposed to a faster-absorbed glucose.

All educational health-promoting activities related to sharing knowledge on a healthy lifestyle, physical activity and diet are significant in gynaecology and obstetrics.

Women with diabetes who plan a pregnancy should remain under the constant care of a diabetic and obstetric team comprising specialists in diabetology, obstetrics, neonatology, ophthalmology and dietetics, along with a nurse educator.

KP-R, GJB, PM and MK designed the manuscript. WK, MM and AB-A provided help and advice on the manuscript. KP-R, GJB, PM, WK, AB-A MM and MK wrote the manuscript. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript.

Not applicable.

Thanks to all the peer reviewers for their opinions and suggestions.

This research received no external funding.

The authors declare no conflict of interest.