There are various hormones released by the placenta namely:
Human chorionic gonadotropin (hCG)- helps in maintaining corpus luteum during early stages of pregnancy.
Estrogens- helps the uterus grow, maintain uterine lining and regulate production of other hormones.
Relaxin- during delivery it relaxes pelvis and widens cervix.
Progestogens- helps in thickening the lining of the uterus during pregnancy.
human placental lactogen (hPL)- it promotes mammary gland growth for lactation.
Final Answer:
The above mentioned points define the answer.