Relaxin is a peptide hormone belonging to the insulin gene superfamily. It is made by the corpora lutea of the ovaries during pregnancy in many mammalian species. The secretion of the hormone into the blood stream just before parturition results in softening and lengthening of the pubic symphysis and a softening of the cervix, which facilitates the process of birth.
Relaxin-1 is proteolytically processed into a hetorodimer that has two peptide chains, A and B that are covalently linked by disulfide bonds.