Montevideo units are a method of measuring uterine performance during labor. They were created in 1949 by two physicians, Roberto Caldeyro-Barcia and Hermogenes Alvarez, from Montevideo, Uruguay. Units are calculated by internally (not externally) measuring peak uterine pressure amplitude (in mmHg) and multiplying by the number of contractions in a 10-minute period. Uterine pressure is generally measured through an intrauterine pressure catheter. Generally, above 200 MVUs is considered necessary for adequate labor during the active phase.