Aim - to develop a method of prevention of major obstetric syndromes (MOS) from the standpoint of a single genesis determined by morphofunctional disorders in the fetoplacental system (FPS), with an assessment of effectiveness by methodological standards of evidence-based medicine Materials and methods. The group I - 32 pregnant women, prevention of MOS was carried out with low doses of acetylsalicylic acid (ASA) at 100-150 mg per os once a day, from 12 to 36 weeks of pregnancy; the group II - 31 pregnant women, who from 6 to 16 weeks were treated prophylactically with progesterone according to the scheme: 200 mg 1 time per day per vagina every day; the group III - 36 pregnant women who received prophylactic monotherapy, consisting of taking magnesium in combination with vitamin B6 for three courses of 6 weeks each; the group IV - 56 pregnant women who refused any preventive measures; the control group (CG) - 50 healthy pregnant women. Тhe effectiveness of prophylactic therapy was evaluated by dynamic examination of the pregnant groups of the study, which included the determination of the following indicators: placental alpha microglobulin (PAMG); placental growth factor; placental protein (PAPP-A), blood leukocyte elevation index, allergy index, concentration of magnesium in blood serum. To objectify the effectiveness of the developed method, the standards of evidence-based medicine were applied. Statistical processing of research results was carried out using standard Microsoft Excel 5.0 and Statistical 6.0 programs. Results. In pregnant women of the group IV, the level of the fibronectin (521±17 μg/ml) increased by an average of 17%, compared to patients of the groups I-III (355±12 μg/ml, 361±13 μg/ml, 368±16 μg/ml; p<0.05), which led to a subsequent increase in the frequency of spontaneous premature births in patients of the group IV; the level of PAMG exceeds the value in the CG by 7.7 times in the group IV; in the group III by 1.7 times, and in pregnant women of groups I and II, it was 25.2±3.8 ng/ml and 26.4±4.2 ng/ml, respectively, against 177±18 ng/ml in group IV (p<0.05). The concentration of the PAPP-A was reduced from the early stages of pregnancy in all studied groups - 6.9±1.8 mg/l, 8.8±1.9 mg/l, 9.2±2.1 mg/l, 7.5±1.6 mg/l (according to the groups I-IV) versus 15.7±2.5 mg/l in the CG (р<0.05). When using the magnesium drug (III group), there are differences with the group IV in most indicators. Conclusions. Methods for the prevention of a complicated course in the high-risk groups for the development of vasculitis when studying personalized and predictive value, which made it possible to divide them in order from more effective to less effective: the method with the appointment of low doses of ASA was in the first place; on the II - prophylactic appointment of micronized vaginal progesterone; on the III - the use of magnesium. The research was conducted according to principles of Declaration of Helsinki. Protocol of research was proved by local ethical committee, mentioned in institution’s work. A informed sonsennt was collected in order to carry out the research. The author is stating no conflict of interests is declared.