To study defects and chromosomal abnormalities of the fetus, we retrospectively analyzed results of comprehensive dynamic survey of 26,404 pregnant women aged 1850 years old at 6 to 40 weeks of pregnancy. Of them, 25,956 (98.3%) women had physiological course of pregnancy, 448 (1.7%) women had abnormal pregnancy. For the diagnosis of fetal defects, we carried out ultrasound, biochemical, invasive and cytogenetic studies. The results of study showed that the majority of fetal defects and pathological course of pregnancy was noted in women at the age of 2125 years old, since at this age period women have the highest number of pregnancies. At the older age, we noted a gradual decrease in the number of pregnant women, as well as the number of abnormalities of the fetus. Based on the analysis of the results obtained, we have developed an algorithm for early fetal ultrasound examination. In order to exclude nondeveloping pregnancy and intrauterine fetal death, as well as for early diagnosis of fetal defects, we recommend screening women in the first trimester of pregnancy., Shahnoza Kamalidinova, and Literatura