翻译：月经周期子宫内膜变化主要为增生期分泌期和月经期。1、增生期一般为月经周期的第1～14天在周期的第一天下丘脑释出促性腺素释放激素刺激垂体释出卵泡刺激素和黄体生成素

Translation: The changes in the endometrium during the menstrual cycle mainly include the proliferative phase, secretory phase, and menstrual phase.

1. Proliferative phase: Generally occurs from the 1st to the 14th day of the menstrual cycle. On the first day of the cycle, the hypothalamus releases gonadotropin-releasing hormone, which stimulates the pituitary gland to release follicle-stimulating hormone and luteinizing hormone.