To examine the benefits of short coincubation of gametes compared to prolonged incubation in in vitro fertilization (IVF).
Design:
Prospective randomized controlled study.
Setting:
Hospital-based fertility center.
Patient(s):
One hundred thirty patients (group 1) and 129 patients (group 2).
Intervention(s):
Oocytes from group 1 were exposed to spermatozoa for 2 hours, and oocytes from group 2 were exposed to spermatozoa for 20 hours.
Main outcome measure(s):
Fertilization and cleavage rates, embryo quality, and pregnancy and implantation rates were evaluated. Estradiol (E2) and progesterone (P4) 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.
Result(s):
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 E2 and P4 in the 20-hour cultures compared with the 2-hour cultures may have been detrimental to embryo quality, pregnancy, and implantation rates.
Conclusion(s):
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.