Preconception

Although the physiological changes of pregnancy develop simultaneously across many systems, different processes may dominate at different stages. In early pregnancy, hormonal shifts, restructuring of vascular tone, activation of the thyroid gland, and increased toxic load associated with the processing of a large volume of hormonal metabolites are more pronounced. In mid-pregnancy, the increasing metabolic load and the expansion of circulating blood volume come to the forefront. In late pregnancy, mechanical and compressive factors related to uterine growth become more prominent.

Pregnancy is a period when the body begins to function under significantly altered conditions. Within a short time, the systems of circulation, digestion, hormonal regulation, immunity, metabolism, and the functioning of internal organs undergo restructuring. These changes are normal and are aimed at the development of the child; however, they require a large amount of resources and stability of all physiological processes.