Serum and follicular fluid leptin during in vitro fertilization: relationship among leptin increase, body fat mass, and reduced ovarian response. - Butzow,T.L.; Moilanen,J.M.; Lehtovirta,M.; Tuomi,T.; Hovatta,O.; Siegberg,R.; Nilsson,C.G.; Apter,D. (J Clin Endocrinol Metab, 1999)