Noun | 1. | ![]() uterine contraction - a rhythmic tightening in labor of the upper uterine musculature that contracts the size of the uterus and pushes the fetus toward the birth canal effacement - shortening of the uterine cervix and thinning of its walls as it is dilated during labor maternity, pregnancy, gestation - the state of being pregnant; the period from conception to birth when a woman carries a developing fetus in her uterus premature labor, premature labour - labor beginning prior to the 37th week of gestation asynclitism, obliquity - the presentation during labor of the head of the fetus at an abnormal angle |