Fetal heart rate tracings in fetuses with congenital malformations.

The fetal heart rate (FHR) tracings of 73 fetuses with gross congenital malformations were surveyed. Fifty-four percent of the tracings were pathologic. The most common pathologic tracing patterns were baseline bradycardia (30%), variable decelerations (25%), baseline tachycardia (22.5%) and decreased variability (20%). There was no characteristic tracing pattern for the whole group or any specific subgroup of malformations. The highest rates of pathologic FHR tracings were found in the groups with multiple malformations (83.3%), chromosomal aberrations (81.8%) and central nervous system lesions (71.4%). Twenty-three infants died neonatally, and 73.9% of them had pathologic FHR tracings. The rate of cesarean section was significantly higher in the group of malformed fetuses--17.8% as compared to 9.5% in the control group. Five of 13 malformed infants delivered by cesarean section died after delivery. Low birth weight and prematurity were more common in the group of malformed fetuses than in the control group. The fact that pathologic FHR tracing patterns occur both in the presence of a malformed fetus and as a result of fetal distress should suggest an early diagnosis of fetal malformation in order to avoid unnecessary obstetric interventions.