Four-channel tocography in uneventful pregnancies: A prospective study in primigravidas and multigravidas

OBJECTIVE: The simultaneous recording of external uterine pressure in four locations on the abdominal wall with four-channel-tocography provides new w ays to describe the dynamics of uterine activity. METHODS: Fifty-eight primigravidas and 25 healthy multigravidas were studie d prospectively with four-channel tocography during the course of pregnancy . Starting at 21 weeks' gestation, the following five intervals were define d: 21-24, 25-28, 29-32, 33-36 and more than 37 completed weeks. Eligibility criteria included informed consent, no history of malformations of the ute rus, and no previous preterm deliveries. Patients were excluded for the fol lowing reasons: medication for preterm labor, cerclage, placenta previa, de livery before 37 weeks' gestation, less than three measurements completed, and patient's withdrawal of consent. RESULTS: The median contraction frequency per hour was six for primigravida s and five for multigravidas, without significant correlation with gestatio nal age. At all time periods studied, the median rate of global contraction s developing simultaneously in at least three uterine segments was less tha n 15%; however, it was significantly higher in primigravidas than in multig ravidas (14% versus 4%, P < .001). Both groups had more activity in the rig ht upper quadrant of the uterus shortly before delivery. CONCLUSION: Foul-channel tocography provided insight into uterine activity patterns and might enable obstetricians to select clinically relevant contr actions for further treatment. Copyright (C) 2001 by the Society for Gyneco logic Investigation.