目的探讨蓖麻油引产餐用于足月妊娠引产时，血清中雌孕激素、皮质醇及胎盘泌乳素水平变化，阐明蓖麻油引产餐发动分娩的内分泌机制。方法应用放射免疫法测定足月妊娠引产５７例血清相关激素水平，其中成功引产３２例（Ａ组），未成功２５例（Ｂ组），分娩自然发动３４例（Ｃ组）。结果Ａ组在不同时期（临产前、临产时、临产后）血清中皮质醇（Ｃｏ）及胎盘泌乳素（ＨＰＬ）水平均有显著上升（Ｐ＜０．０１），且与Ｃ组一致；Ａ组３个不同时期血清雌二醇（Ｅ２）、雌三醇（Ｅ３）水平有不同程度上升，孕酮（Ｐｒ）下降，但无显著性（Ｐ＞０．０５）；Ａ组临产时Ｃｏ，ＨＰＬ水平高于未成功组，差异显著（Ｐ＜０．０１），Ｅ２，Ｅ３及Ｐｒ水平无显著差异（Ｐ＞０．０５）。结论Ｃｏ、ＨＰＬ参与蓖麻油引产餐引产的发动，且与分娩的进展有关，未达到一定水平，分娩不能发动，引产失败 Objective To investigate the changes of estrogen, progesterone, cortisol and placental prolactin levels in cesarean section during full term pregnancy induced labor, and to elucidate the endocrine mechanism of castor oil induced labor initiation. Methods Fifty-seven cases of labor-related pregnancy induced abortion were measured by radioimmunoassay. Among them, 32 cases were successful induction of labor (group A), 25 cases were unsuccessful (group B) and 34 cases started spontaneous labor (group C). Results Serum cortisol (Co) and placental prolactin (HPL) levels in group A at different periods (before labor, during labor and after labor) were significantly increased (P <0.01), and were consistent with those in group C; A Serum estradiol (E2) and estriol (E3) levels increased in three different periods in the three groups, while progesterone (Pr) decreased, but no significant difference (P> 0.05) The level of HPL was higher than that of the unsuccessful group (P <0.01). There was no significant difference in the levels of E2, E3 and Pr (P> 0.05). Conclusions Co and HPL are involved in the initiation of labor induction of castor oil during labor and are related to the progress of labor and have not reached a certain level. Labor can not be started and labor induction fails