title: Factors influencing serum progesterone level on triggering day in stimulated in vitro fertilization cycles.
abstract: OBJECTIVE
  Elevated serum progesterone (P) levels on triggering day have been known to affect the pregnancy rate of in vitro fertilization (IVF). This study aimed to identify the possible factors influencing serum P levels on triggering day in stimulated IVF cycles.
  
  
  METHODS
  Three hundred and thirty consecutive fresh IVF cycles were included in the study. All cycles were first attempts and were performed in a single infertility center. The indications for IVF were male factor infertility (n=114), ovulatory infertility (n=84), endometriosis (n=61), tubal infertility (n=59), unexplained infertility (n=41), and uterine factor infertility (n=39). A luteal long protocol of a gonadotropin-releasing hormone (GnRH) agonist (n=184) or a GnRH antagonist protocol (n=146) was used for pituitary suppression. Ovarian sensitivity was defined as the serum estradiol level on triggering day per 500 IU of administered gonadotropins (OS[a]) or the retrieved oocyte number per 500 IU of administered gonadotropins (OS[b]).
  
  
  RESULTS
  Univariate analysis revealed that the serum P level on triggering day was associated with the serum estradiol level on triggering day (r=0.379, p<0.001), the number of follicles ≥14 mm (r=0.247, p<0.001), the number of retrieved oocytes (r=0.384, p<0.001), and ovarian sensitivity (OS[a]: r=0.245, p<0.001; OS[b]: r=0.170, p=0.002). The woman's age, body mass index, antral follicle count, and basal serum follicle stimulating hormone and estradiol levels were not associated with serum P level on triggering day. The serum P level on triggering day did not show significant variation depending on the type or cause of infertility, pituitary suppression protocol, or the type of gonadotropins used.
  
  
  CONCLUSIONS
  The serum P level on triggering day was closely related to the response to ovarian stimulation.
authors.affiliation: M Fertility Center, Seoul, Korea.
authors.forename: Ju Hee
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam, Korea. ; Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Byung Chul
authors.initials: BC
authors.lastname: Jee
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea. ; Department of Obstetrics and Gynecology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Seok Hyun
authors.initials: SH
authors.lastname: Kim
keywords: Estradiol; In vitro fertilization; Ovarian stimulation; Progesterone