妊娠期黄体酮水平急剧增高,于妊娠末期可高达基础值的50～100倍。高浓度黄体酮可抑制子宫平滑肌裂隙连接的形成,而致子宫显著舒张及收缩不良。至分娩前黄体酮水平迅速降低,因而子宫强烈收缩。有人提出黄体酮亦可作用于其它部位的平滑肌,例如妊娠晚期常有食道括约肌松弛而出现反流症状。如果此种作用可影响支气管平滑肌,则对哮喘的孕妇有明显的临床影响,Glack 发现,妊娠期14%的患者哮喘症状改善,43%恶化;White 等发现69%改善,仅6%恶化;而 Schaefer 等报道293例孕妇中93%哮喘症状无改变。Juniper 等最近对20例有生育力的哮喘妇女进行前瞻性研究,结果表明16例患者孕期的黄体酮水平与支气 Gestational progesterone levels increased dramatically in the late pregnancy can be as high as 50 to 100 times the basal value. High concentrations of progesterone can inhibit the formation of uterine smooth muscle gap junction, which caused significant diastolic and systolic dysfunction. Progesterone levels rapidly decrease until delivery, and the uterus contracts strongly. It was suggested that progesterone may also act on other parts of the smooth muscle, such as the late third trimester of the esophageal sphincter relaxation and reflux symptoms. Glack found that asthma symptoms improved and 43% worsened in 14% of pregnant women; White et al. Found a 69% improvement and only a 6% worsening, with bronchial smooth muscle, which had a clinically significant effect on pregnant women with asthma Schaefer et al. Reported that 93% of 293 pregnant women had no change in asthma symptoms. Juniper et al recently conducted a prospective study of 20 fertile asthmatic women and found that progesterone levels and bronchial