THE EFFECT OF UTERINE CONTRACTIONS ON INTRAPARTUM FETAL HEART-RATE ANALYZED BY A COMPUTERIZED SYSTEM

OBJECTIVE: Our goal was to assess the effect of uterine activity on fe tal heart rate indexes during the active phase of labor with a compute rized fetal heart rate monitoring system. STUDY DESIGN: Twenty-six hea lthy women were studied in active labor without analgesia. Fetal heart rate was analyzed by a computerized system (Sonicaid, System 8000), p roviding a numeric analysis of the fetal heart rate indexes. Montevide o and Alexandria units were used for quantitative assessment of contra ctions. RESULTS: A significant correlation was found between Montevide o units and short-term variation (r = -0.62, p < 0.001), episodes of h igh (r = -0.48, p < 0.01) and low (r = 0.58, p < 0.01) fetal heart rat e variation, and frequency of large accelerations (r = -0.49, p < 0.01 ). A significant correlation was also found between Alexandria units a nd short-term variation (r = -0.645, p < 0.001), episodes of high feta l heart rate variation (r = -0.58, p < 0.01), and frequency of large a ccelerations (r = -0.49, p < 0.01). CONCLUSIONS: In active labor fetal heart rate variability is significantly affected by the intensity and duration of contractions.