Research objective: to assess the course and consequences of pregnancy in women with vitamin D lack and deficit that is adjusted with DeviSol Strong at the pre-pregnancy preparation or during pregnancy.Materials and methods. The study involved 145 women aged 18 to 30 years. Experimental cohort (120 women with vitamin D deficiency) was divided into three groups: the first group – 40 pregnant women, the second group – 50 patients at the stage of pre-pregnancy preparation, comparison group – 30 pregnant women at 6–10 weeks of gestation. Control group consisted of 25 pregnant women with sufficient levels of vitamin D. 25(OH)D value in serum was determined by immunochemical method with chemiluminescent detection. DeviSol Strong dietary supplement was chosen to correct vitamin D deficiency. It was administered differently, based on 25(OH)D level.Results. Patients receiving 800 IU/day of cholecalciferol showed an increase in the vitamin D deficiency (from 46.7% to 76.7%). Vitamin D deficiency was reduced from 75.0% to 32.5% in women who received 2000 IU and 4000 IU of cholecalciferol for 3 months, the proportion of pregnant women with severe vitamin D deficiency decreased by 2,4 times. A rapid positive effect was achieved in 82.0% of pre-pregnancy patients receiving DeviSol Strong 4000 IU/day or 6000 IU/day (4000 IU + 2000 IU).Abortion risk before 12 weeks of gestation occurred in 23.3% of women in the comparison group, in 7.5% of pregnant women in group 1, in 4.0% in control group and in 2.0% in group 2. Early miscarriage occurred in 3,3% of patients in the comparison group. 13.3% of pregnant women in the comparison group, 5.0% from group 1 and 2.0% from group 2 were hospitalized with the threat of premature birth, premature birth occurred in one patient of the comparison group.Conclusions. Assessment of the first half of pregnancy with differentiated correction of vitamin D deficiency indicates the need for supplementation of cholecalciferol at the stage of pre-pregnancy preparation for prevention of gestation complications. DeviSol Strong is an effective drug for correcting vitamin D deficiency. Most effective dose in severe vitamin D deficiency is 6000 IU (4000 IU + 2000 IU), 4000 IU in lack and deficiency, which allowed achieving an adequate 25(OH)D level after 3 months in 82% of patients.