Uterine contractions means contractions of uterus that are produced in order to expel the contents of the uterus out side. These contents of uterus can be baby or linings of the uterus.At the time of delivery, uterine contractions are produced to deliver the baby and this contraction is sign of labor. When periods starts in a lady, uterine contractions expel the uterine linings to clear the uterus and prepare for implantation during current cycle.