During the Medical US check-up, some mothers-to-be will hear that their foetus is too small or too large compared to other foetuses at the same stage of pregnancy. The dynamics of intrauterine growth affect not only the wellbeing of the baby during pregnancy, but also the course of the birth and the state of health even into adulthood! It is therefore worth learning about the causes of fetal growth disorders in the womb, as well as ways of preventing the unpleasant consequences of these phenomena.