Oral contraceptive therapy reduces serum relaxin‐2 in elite female athletes

• Published in: The journal of obstetrics and gynaecology research 2017-03, Vol.43 (3), p.530-535
• Main Authors: Nose‐Ogura, Sayaka, Yoshino, Osamu, Yamada‐Nomoto, Kaori, Nakamura, Mariko, Harada, Miyuki, Dohi, Michiko, Okuwaki, Toru, Osuga, Yutaka, Kawahara, Takashi, Saito, Shigeru
• Format: Article
• Language: English
• Subjects: 17β-Estradiol; Adult; Amenorrhea - blood; Anterior cruciate ligament; anterior cruciate ligament (ACL); Athletes; Contraceptives, Oral - blood; Estradiol - blood; Female; Follicle Stimulating Hormone - blood; Follicle-stimulating hormone; Hogs; Humans; Knee; luteal phase; Luteinizing hormone; Luteinizing Hormone - blood; menstrual cycle; Menstrual Cycle - blood; oral contraceptive (OC); Oral contraceptives; Progesterone; Progesterone - blood; Relaxin; Relaxin - blood; relaxin‐2; Young Adult
• ISSN: 1341-8076; 1447-0756
• DOI: 10.1111/jog.13226

Aim Recent investigations have demonstrated that athletes with high relaxin‐2 levels have a high risk of anterior cruciate ligament injuries, while athletes taking oral contraceptives (OC) have low relaxin‐2 levels. It has not yet been clarified whether taking OC reduces relaxin‐2 levels. The purpose of this study was to investigate changes in relaxin‐2 levels in athletes taking OC. Methods Levels of relaxin‐2, estradiol, progesterone, luteinizing hormone and follicle‐stimulating hormone were measured in serum samples (n = 183) from 106 elite female athletes. Five athletes with serum relaxin‐2 concentrations > 6 pg/mL during the luteal phase were recruited to assess the effect of OC therapy. Results Serum relaxin‐2 concentrations were significantly higher during the luteal phase (n = 57) than in the follicular phase (n = 72), or in athletes on OC therapy (n = 10) (P < 0.001, P < 0.001 and P < 0.05, respectively). In the luteal phase, 36.8% (21/57) of the athletes had relaxin levels > 6 pg/mL. In 23 athletes, serum relaxin‐2 concentrations were measured during both the follicular and luteal phases, revealing that relaxin‐2 levels were significantly higher in the luteal phase compared with the follicular phase. In 5 out of 23 athletes, serum relaxin‐2 concentrations were > 6 pg/mL in the luteal phase and during the second cycle of OC therapy, relaxin‐2 concentrations decreased dramatically to below the detection limit (0.26 pg/mL). Conclusions High serum relaxin‐2 concentrations were only detected during the luteal phase. In athletes with high relaxin‐2 concentrations during the luteal phase, OC therapy decreased serum relaxin‐2 levels.