妊娠时黄体酮水平急剧升高,妊娠后期达高峰,为基础值的50～100倍。高水平黄体酮抑制了子宫平滑肌的裂隙接点的形成,使子宫松弛、收缩力差。分娩前黄体酮水平迅速下降,裂隙接点形成突然增加,子宫收缩力随之加强。这种激素对平滑肌的作用也可见于身体的其他部位,如妊娠晚期食管括约肌松弛导致食物反流。支气管平滑肌可能也类似,妊娠时处于相对松弛状态,分娩时收缩性增加。如情况确实,那么那些长期发作和有支气管平滑肌肥厚的哮喘 Progesterone levels during pregnancy, a sharp increase in late pregnancy reached its peak, based on the value of 50 to 100 times. High levels of progesterone inhibit the formation of uterine smooth muscle fissure junction, so that uterine relaxation, contractility poor. Preterm delivery progesterone levels decreased rapidly, the sudden formation of crevice joints, uterine contractility then strengthened. The effect of this hormone on smooth muscle can also be found in other parts of the body, such as lax esophageal sphincter during late pregnancy leads to food reflux. Bronchial smooth muscle may also be similar, in a relatively relaxed state of pregnancy, contractions during childbirth increased. If this is the case, then those long-term attacks and bronchial smooth muscle hypertrophy of asthma