Answer:
During the three trimesters of pregnancy, a woman´s body becomes literally a carnival of rising and dropping hormones, and other substances, that will both help the baby develop, and prepare the mother to meet the demands of the baby, and those of her own body, so that pregnancy is a success.
While at the first trimester the most common to find are HCG, estrogen and progesterones, as well as some others, this changes, especially in the case of HCG. But throughout the second, and third trimester, we have a set of hormones that never drop, as they are the main responsible for the maintenance of the pregnancy; these are estrogen and progesterone. The field changes on the third trimester, with the appearance of several other hormones that start preparing the mother for labor, and for the after, including lactation.
Given what is said above, the answers would be thus:
The 3 hormones that rise at the end of the pregnancy are: estrogen, progesterone and oxytocin. This last one initiates the preparation of the mother´s muscles for labor. The former ones also prepare both baby, placenta, and other portions, for labor. And the non hormone would be: prostaglandins, whose role is to initiate the relaxation of the cervix so that birth can go smoothly.
