SERUM LEVELS OF RELAXIN DURING THE MENSTRUAL-CYCLE AND ORAL-CONTRACEPTIVE USE

Serum relaxin levels were analysed in 12 healthy women every other day during the menstrual cycle and during a second cycle on oral contrace ptives. Relaxin levels in 7 women with posterior pelvic and lumbar pai n were also measured. Relaxin was detected during both the follicular and luteal phases of the menstrual cycle in some of the healthy women. Serum levels were further increased during the use of oral contracept ives. Oestradiol levels in the untreated women correlated to the relax in levels. Women with posterior pelvic and lumbar pain had higher rela xin levels than did healthy women, a finding that needs to be further explored. Our data indicate the existence of sources for relaxin produ ction other than the corpus luteum in the non-pregnant woman. Endogeno us and exogenous oestrogens may stimulate the production of relaxin.