title: The significance of coasting duration during ovarian stimulation for conception in assisted fertilization cycles.
abstract: BACKGROUND
  Withholding gonadotrophin administration and postponing HCG injection, termed coasting, has been suggested as a treatment modality in cases of impending ovarian hyperstimulation syndrome (OHSS). It presents an opportunity to reduce the risk of OHSS and salvage the treatment, without apparent compromise to outcome. However, the duration of the coasting period, which would maintain the advantage without reducing conception rate, has not been fully established. In this retrospective study, we attempted to define the optimal interval of coasting in patients at risk of developing OHSS.
  
  
  METHODS
  Patients were grouped according to the number of days elapsed between cessation of gonadotrophins and administration of HCG. Overall, out of 207 patients (mean age 30.76 +/- 0.33 years) coasting lasted 1 day in 39 cycles (18.8%), 2 days in 61 cycles (29.4%), 3 days in 49 cycles (23.6%) and > or = 4 days in the remaining 58 cycles (28.5%).
  
  
  RESULTS
  There was no difference between the groups in patients' age, serum estradiol concentrations at the time of HCG administration, oocyte maturity, fertilization and embryo cleavage rates. However, patients in whom coasting lasted > or = 4 days had significantly reduced implantation (10.5%) and pregnancy (26.7%) rates compared with patients with a shorter coasting interval (ranges 18.4-27.9 and 41-55.7% respectively; P < 0.05).
  
  
  CONCLUSIONS
  Coasting for >3 days appears to reduce implantation and pregnancy rates while in-vitro oocyte and embryo quality do not appear to be affected. We suggest that in patients who need coasting for >3 days, cryopreservation of embryos should be considered.
authors.affiliation: Bahceci Women's Health Care Center and German Hospital at Istanbul, Istanbul, Turkey.
authors.forename: Ulun
authors.initials: U
authors.lastname: Ulug
authors.forename: Mustafa
authors.initials: M
authors.lastname: Bahceci
authors.forename: Halit F
authors.initials: HF
authors.lastname: Erden
authors.forename: Eliezer
authors.initials: E
authors.lastname: Shalev
authors.forename: Izhar
authors.initials: I
authors.lastname: Ben-Shlomo
mesh_terms: D000328:Adult; D006063:Chorionic Gonadotropin / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D010064:Embryo Implantation; D005260:Female; D006062:Gonadotropins / Q000008:administration & dosage*; D006801:Humans; D016471:Ovarian Hyperstimulation Syndrome / Q000517:prevention & control*; D011247:Pregnancy; D018873:Pregnancy Rate; D012099:Reproductive Techniques; D012189:Retrospective Studies
chemical_list: D006063:Chorionic Gonadotropin; D006062:Gonadotropins