Relaxin - Reproduction
This is a water soluble hormone present in the ovaries, placentae and uteri of various mammalian species during pregnancy. Its role in human physiology is not clear. It is apparently a hormone of pregnancy and has not been found in the blood of men or non- pregnant women.
Relaxin levels in the blood reach a high peak during the terminal stages of pregnancy and disappear within one day after delivery. It is thought-that relaxin helps in the enlargement of birth canal by relaxation of uterine cervix and pelvic ligaments.