Overweight and obesity are a serious problem of our time. According to data from the World Health Organization (WHO) from 2016, about 1.9 billion people are overweight, of which 650 million have varying degrees of obesity. Being overweight leads to a number of health problems: increased blood pressure, increased risk of cardiovascular events, dyslipidemia, type 2 diabetes, as well as problems with the menstrual cycle and infertility. To determine the degree of obesity, the so-called body mass index (BMI – body mass index). It is calculated by dividing the body weight in kilograms by the square of the height in meters. People with a body mass index below 18.5 are defined as underweight. A BMI between 18.5 and 24.9 is considered normal. Patients with a body mass index between 25 and 29.9 are defined as overweight, and patients with a BMI over 30 are diagnosed as obese. Depending on the body mass index, three degrees of obesity are distinguished: Obesity class I – BMI between 30 and 34.9; Obesity class II – BMI between 35 and 39.9; Obesity Class III – BMI over 40. Obesity has been found to lead to menstrual cycle problems such as oligomenorrhea, anovulatory cycles, dysmenorrhea, as well as problems conceiving and complications during pregnancy. But what are these obesity problems due to? 1. An increase in body mass index above the optimal, especially in the form of visceral obesity (accumulation of fatty tissue around the organs in the abdominal cavity) leads to hormonal imbalance, increases estrogen levels and decreases sex hormone binding globulin (SHBG) levels . It is a globulin responsible for transporting sex hormones, and its low levels are associated with conditions such as insulin resistance, obesity, polycystic ovary syndrome, etc. 2. Obesity leads to a disturbance in the activity of the hypothalamus-pituitary-ovary axis – the production of luteinizing (LH) and follicle-stimulating (FSH) hormones from the pituitary gland, which are responsible for the maturation of the egg, the ovulation process and the formation of the yolk, is suppressed body. Suppression of the activity of these hormones leads to anovulatory cycles and difficulties in conceiving. 3. Very often obesity is a symptom of polycystic ovary syndrome (PCOS), in which subfertility (reduced fertility) is observed in a large percentage of cases. Due to the chronic inflammation in the body of such patients, inflammatory mediators such as interleukin-6, tumor necrosis factor, etc. are produced, which cause beta-cell dysfunction of the pancreas and lead to insulin resistance. On the other hand, reducing body weight by 5-10% increases the chances of getting pregnant. In this regard, proper diet and moderate physical activity are the main ways to deal with the problems that obesity creates. In addition to fertility,overweight also affects the course of pregnancy. Among pregnant women suffering from obesity, the risk of complications such as pre-eclampsia, development of type 2 diabetes mellitus, premature birth, development of gestational diabetes and the birth of an overweight child is increased. The risks of cesarean birth are also increased and the subsequent recovery process is delayed. A common pathological condition among obese patients is obstructive sleep apnea – periods of partial (hypopnea) or complete (apnea) cessation of breathing during sleep. During pregnancy, periods of hypopnea and apnea can lead to fetal growth retardation. Obesity is a serious problem that has a significant negative impact not only on the reproductive capabilities of men and women, but also on the overall functioning of the human body. The combination of a balanced diet, increased physical activity, reduced stress levels and optimal rest time lead to a reduction in body weight and increase the chances of getting pregnant and giving birth to a healthy child.