title: Short coincubation of gametes in in vitro fertilization improves implantation and pregnancy rates: a prospective, randomized, controlled study.
abstract: OBJECTIVE
  To examine the benefits of short coincubation of gametes compared to prolonged incubation in in vitro fertilization (IVF).
  
  
  METHODS
  Prospective randomized controlled study.
  
  
  METHODS
  Hospital-based fertility center.
  
  
  METHODS
  One hundred thirty patients (group 1) and 129 patients (group 2).
  
  
  METHODS
  Oocytes from group 1 were exposed to spermatozoa for 2 hours, and oocytes from group 2 were exposed to spermatozoa for 20 hours.
  
  
  METHODS
  Fertilization and cleavage rates, embryo quality, and pregnancy and implantation rates were evaluated. Estradiol (E(2)) and progesterone (P(4)) levels were measured in the wells of culture dishes after 2-hour exposure of oocytes/zygotes to spermatozoa in group 1 and after 20-hour exposure in both the groups.
  
  
  RESULTS
  There was no difference between the two groups in the fertilization rate and the number of embryos obtained. However, the proportion of grade 1 embryos was significantly higher among group 1 compared to group 2 patients. Clinical pregnancy and implantation rates were significantly higher among group 1 compared to group 2. The significantly higher levels of E(2) and P(4) in the 20-hour cultures compared with the 2-hour cultures may have been detrimental to embryo quality, pregnancy, and implantation rates.
  
  
  CONCLUSIONS
  Coincubation of gametes for 2 hours with standard or high insemination concentrations of spermatozoa significantly improved embryo quality and the pregnancy and implantation rates compared with overnight incubation of gametes.
authors.affiliation: Centre for Reproductive Medicine and Gleneagles IVF Centre, Gleneagles Hospital, Singapore. kattera@singnet.com.sg
authors.forename: Suresh
authors.initials: S
authors.lastname: Kattera
authors.forename: Christopher
authors.initials: C
authors.lastname: Chen
mesh_terms: D000328:Adult; D018920:Coculture Techniques; D010064:Embryo Implantation; D004958:Estradiol / Q000378:metabolism; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007246:Infertility / Q000628:therapy*; D008297:Male; D009865:Oocytes / Q000378:metabolism; D011247:Pregnancy; D018873:Pregnancy Rate; D011374:Progesterone / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism; D013997:Time Factors
chemical_list: D011374:Progesterone; D004958:Estradiol