3) Effect of relaxin
Relaxin is secreted first by the corpus luteum, placenta and later by the endometrium to facilitates delivery in three ways:
a) It increase the number of oxytocin receptors in the uterus
b) It facilitate the passage of fetus through the cervix during delivery
c) It causes relaxation of the pelvic ligaments which leads to easing the passage of fetus through the birth canal.
4) Effect of Progesteron
It inhibit uterine contraction, in some women progesterone level decline just before delivery that will facilitate the onset of labor. Also some evident indicate that the placenta may secret a progesterone binding protein before labor which in turn reduces the amount of free progesterone in maternal level and this will lead to facilitate labor.