The progesterone and estradiol continue the hypertrophy of endometrial lining in the uterus and fallopian tubes and maintain it throughout pregnancy. Progesterone is also necessary for the proper implantation of the foetus in the uterine wall. It stimulates the endometrial glands to secrete a nutrient fluid for the foetus, hence the term secretory phase. The progesterone inhibits the release of FSH so that it may not develop additional follicles and eggs.