Spontaneous prolonged contractions during antenatal fetal heart rate monitoring.

Uterine contractions of more than 2 minutes' duration occurred spontaneously in 1.4% of 6,399 antenatal fetal heart rate (FHR) recordings. All recordings were made in the Department of Obstetrics and Gynaecology at Tygerberg Hospital. The patients with spontaneous prolonged contractions (SPC) were compared with a randomly selected control group. Patients who had an SPC during antenatal FHR recording were not at a higher risk of abruptio placentae, preterm labour or unexpected intra-uterine death. Of the infants born to the mothers in the study group, 65.5% were male. There were more primigravidas in the study group, which may have been responsible for the longer duration of the second stage of labour in this group. When primigravidas only were examined no difference between the two groups could be found except for a larger placental mass in the study group. It is uncertain why primigravidas were more likely to develop SPCs as observed during antenatal FHR monitoring.