Relevance much attention is paid to the problem of the effect of extrasystolic arrhythmia in pregnant women on the condition of the fetus. The aim of the study is to study the effect of extrasystolic arrhythmia in pregnant women on the condition of the fetus by cardiotocography. Material and methods. 32 pregnant women with extrasystole (group 1) and 30 without arrhythmia (group 2) were examined in the 3rd trimester from the 32nd week of pregnancy. All pregnant women of both groups underwent daily registration of electrocardiography (ECG), ultrasound examination of the heart, fetal cardiotocography (CTG of the fetus), determination of the level of human chorionic gonadotropin (hCG), prolactin and thyroid hormones. Results. The correlation analysis revealed a close relationship between the number of fetal cardiotocography scores and the level of thyroid-stimulating hormone (TSH) (r = 0,917, p <0,01), free thyroxine (T4c) (r = -0,877, p < 0,01) and the number of extrasystoles (r = -0,872, p < 0,01) in pregnant women. Conclusion. In pregnant women with and without extrasystole, there are differences between reproductive hormones and electrocardiography indicators within the reference values. It was found that in pregnant women with and without extrasystole, fetal cardiotocography indicators do not significantly differ. A quantitative threshold value of ventricular extrasystole was revealed to reduce the number of fetal cardiotocography scores in the third trimester from week32. The threshold value of extrasystole was 1500 per day, AUC (area under curve) – 0,792, sensitivity – 81,3 %, specificity – 100,0 %.