Essential factors of labor(12) LABOR FORCE-- retraction
Retraction: retraction is a phenomenon of the uterus in labor in which the muscle fibres are permanently shortened, it is different from the contraction.
Retraction is specially a property of upper uterine segment. Contraction is a temporary reduction in length of the fibres, which attain their full length after the contraction passes off. In contrast, retraction results in permanent shortening and the fibres are shortened once and for all.
When the active contraction passes off the fibres lengthen again, but not to their original length.