Fertilization rate is an independent predictor of implantation rate.
OBJECTIVE
To determine whether fertilization rate serves as a biological assay, reflects oocyte quality, and may be used to help predict patient implantation rate.


METHODS
Retrospective cohort study.


METHODS
Academic center.


METHODS
Couples undergoing 3603 in vitro fertilization (IVF) cycles from 2001 to 2007.


METHODS
None.


METHODS
We compared the implantation rate among cycles with high versus low fertilization rate. Univariate analyses were performed to determine the association of implantation rate with potential confounding variables: age, day-3 follicle-stimulating hormone level, day-3 estradiol level, antral follicle count, oocyte number, cycle attempts, embryo grading, and number of embryos transferred. Multivariate analysis was then performed to determine whether the fertilization rate remained an independent predictor.


RESULTS
Cutoffs for fertilization rate were 50% for intracytoplasmic sperm injection (ICSI) and 75% for conventional insemination. Higher ICSI fertilization was statistically significantly associated with the implantation rate (25.2% vs. 17.8 %). After adjusting for variables associated with implantation rate, fertilization rate for ICSI remained a strong independent predictor of implantation. Higher conventional insemination fertilization was statistically significantly associated with implantation (32.1% vs. 25.7%) and remained a statistically significant predictor after adjustment.


CONCLUSIONS
Fertilization is a strong, independent predictor of implantation rate and may be useful in modeling to guide decision making for the number of embryos to transfer.
Rosen
Mitchell P
MP
Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California. Electronic address: rosenm@obgyn.ucsf.edu.
Shen
Shehua
S
Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California.
Rinaudo
Paolo F
PF
Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California.
Huddleston
Heather G
HG
Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California.
McCulloch
Charles E
CE
Department of Epidemiology and Biostatistics, University of California, San Francisco, California.
Cedars
Marcelle I
MI
Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California.
D000328:Adult; D015331:Cohort Studies; D003657:Decision Making; D010064:Embryo Implantation / Q000502:physiology*; D004624:Embryo Transfer / Q000379:methods; D015981:Epidemiologic Factors; D005260:Female; D005306:Fertilization / Q000502:physiology*; D006801:Humans; D007246:Infertility / Q000175:diagnosis* / Q000628:therapy*; D008297:Male; D009865:Oocytes / Q000166:cytology; D011247:Pregnancy; D018873:Pregnancy Rate; D011379:Prognosis; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic / Q000706:statistics & numerical data*; D016896:Treatment Outcome