Units are calculated by internally (not externally) measuring uterine pressure above baseline tone and multiplying by the number of contractions in a 10 minute period. Uterine pressure is generally measured through an intrauterine pressure catheter.
Montevideo units can be more simply calculated by summing the individual contraction intensities in a ten minute period, a process which should arrive at a result identical to the original method of calculation.
Generally, above 200 MVUs is considered necessary for adequate labor during the active phase.
If, for instance:
- uterine pressure above baseline were 50 mmHg
- during the 10 minute period of measurement 3 contractions occurred
- total Montevideo units (MVUs) would be equal to 150 MVUs (50 * 3)
- Montevideo units are calculated by subtracting the baseline uterine pressure from the peak contraction pressure for each contraction in a 10 minute window and by adding the pressures generated by each contraction.
- For example, five contractions occurred, producing pressure changes of 52, 50, 47, 44 and 49 mm Hg, respectively. The sum of these five contractions is 242 Montevideo units.
- "MATERNITY GUIDE - Labor & Delivery". Retrieved 2010-03-28.
- Ball, RH; Espinoza, MI; Parer, JT (1994). "Regional blood flow in asphyxiated fetuses with seizures". Am J Obstet Gynecol 170 (1): 156–261.