Preeclampsia is a leading cause of maternal and perinatal mortality and morbidity up to present. Despite of many prognostication factors, proved on molecular, as well on epidemiological levels, modern obstetrician society is quitely armless not only to prevent, but also to predict severity and term of preeclampsia development.One of the manifestation of correct adaptation to pregnancy is a steady reaction in the acid-base balance, which ensures the constant transport of acidic products of fetal metabolism. The disorder at the level of acid-base and water-electrolyte balances can cause and support pathological processes from 20 week of pregnancy. The fact of preeclampsia substrate grounding in the first trimester of pregnancy does not require evidence today. It is also a time of other gestational manifestation like nausea and vomiting. Prospective observations confirm that women with first- trimester vomiting do not manifest differences in the concentration of main ions, despite the inevitable loss of electrolytes by vomiting, comparing with women without pregnancy associated vomiting. The reduce of sodium ions in the dynamics of pregnancy proves physiological hemodilution. This is the pattern found in the prospective follow-up of women with first-trimester vomiting. On the other hand, women with incomplicated first trimester are more likely to have an increased sodium concentrations in 20-22 weeks of pregnancy. Similar dynamic for hematocrit demonstrates, that women without vomiting in the first months of pregnancy have the tendency for inadeqautehemodilution. It's also confirmed by higher hemoglobin concentration at women without first-trimester vomiting. Despite of absence of difference in main electrolyte concentrations, patients with first-trimester vomiting demonstrate greater trend to alkalosis, measured by hydrogen ion absolute concentration. Inherent in pregnancy expansion of plasma volume leads to the corresponding reduction of relative content of its non-polar substances, primarily proteins, even concerning the physiological growth of fibrinogen. A relative reduction of protein content inevitably affects the oncotic pressure value, the concentration of extracellular fluid, electrolytes. All listed change the colloid-osmotic pressure and hydrostatic balance, and therefore, the distribution of water between the cell and extracellular spaces. Consistency of these processes is a condition of normal adaptation to pregnancy, and their imbalance can cause preeclampsia. The circulation of different classes of antibodies to phospholipids was determined as a possible marker for the further pregnancy progress. Thus, it is proved, that the detection of antibodies rate to one or more phospholipids classes in the first trimester does not exceed the general population and does not depend on first-trimester vomiting. In the same time, a significant increasing of antibodies circulation is discovered whenredefined in women without first-trimester vomiting in second trimester. This change was not proper to patients, having vomiting in first weeks of pregnancy. The prevalence of the antibody to negative phospholipids explanes the role of membraneasymmetry in cell wellbeing regulation, the appearance of antibodies to phospholipid, usually located in inner layer on cellular membrane should be considered as a sign its dysfunction. The incidence of severe preeclampsia is similar among patients having or not vomiting of first trimester and is in accordance with population data. The difference is in term of severe preeclampsia debute - this diagnosis was more rare till 30 gestation weeks among women with first-trimester vomiting comparatively to patients without such a complaint. Besides this, women with incomplicated first trimester are inclined to more frequent hyperfermentemia, thrombocytopenia, and hyperbilirubinemia.
