Relaxin is a peptide hormone having molecular wt. around 6000 Da.
It is secreted in ovaries by corpus luteum and in placenta, playing a major role in female reproductive system during pregnancy.
Its level rise in after the ovulation so as to reduce contractions in uterus as it is thought to get prepared for implantation, this preparing the uterine lining for pregnancy.
It relaxes pubic symphysis (a ligament in pelvis region of female) and widens the cervix during parturition.
The role of relaxin in male is not well describes yet it is believed to increase the sperm movement in semen.