Table 1.

Definitions of contraction parameters

Parameter	Definition*
Frequency	Number of contractions in 10-minute period
Duration	Average time in seconds between the onset of a contraction and return to baseline uterine tone
Relaxation time	Time in seconds between the end of a contraction and the onset of the next contraction summed over a 10-minute period
Montevideo units	Average contraction amplitude in a 10-minute period multiplied by the number of contractions in that period
Baseline uterine tone	Average intrauterine pressure in mmHg between contractions

^*All values averaged over 30 minutes, or amount of time an IUPC was used to measure contractions in the last 30 minutes in labor.