Relaxin is all about keeping the reproductive system relaxed and calm. During a normal menstrual cycle, relaxin follows the same trajectory as progesterone, rising in quantity after ovulation and decreasing with the onset of your period. During pregnancy, it peaks during the first and third trimesters, when it works to prevent early contractions, promote healthy and smooth functioning, and prepare the cervix for birth. While more research is needed, it is thought that relaxin may have some effect in the treatment of the autoimmune disorder scleroderma, which impacts the skin.