[A scoring system for the evaluation of prenatal cardiotocograms: a study on normal patients].

A 10-point scoring system based on the basal heart rate, amplitude and frequency of variation, accelerations and decelerations was developed to assess antenatal fetal heart rate patterns in 47 patients with uncomplicated pregnancies and deliveries. From a gestational age of 28 weeks the fetal heart rate was monitored every 2 weeks until 36 weeks and then every week until delivery, usually by ultrasound. Every 4-minute period of the cardiotocogram was scored and then the mean score was calculated for every test. The mean score for all the tests was 6,9 with a standard deviation of 1,8. In 1 patient a basal bradycardia was responsible for the low score. At the end of the pregnancy, the fetal heart rate in this patient fluctuated between 90 and 110/min. A heart rate above 180/min was seen on three occasions in 3 different patients. Tests before or after these episodes of tachycardia were all normal. Severe variable decelerations and non-reactive heart rate pattern in 1 patient were responsible for the lowest score seen in this study. This patient developed severe variable decelerations during labour; at caesarean section, the umbilical cord was tightly around the neck twice. The difference between the lowest and highest 4-minute scores was called the fluctuation of the score. Between 28 and 36 weeks the mean fluctuation of the score varied between 0,6 and 1,2. After 36 weeks however, the mean fluctuation suddenly increased to 1,67 at 37 weeks and to 1,9 at 38 weeks. After 38 weeks the score fluctuation gradually declined again. The mean score was not influenced by the duration of pregnancy.