A quantitative assessment of follicle size on oocyte developmental competence.
OBJECTIVE
To quantitatively assess the impact of follicle size on oocyte maturation, fertilization, and embryo quality.


METHODS
Prospective study.


METHODS
Academic medical center.


METHODS
Couples undergoing ovarian stimulation and in vitro fertilization (IVF).


METHODS
A total of 235 cycles were monitored prospectively, and 2934 oocytes were collected from five groups of follicle size. Repeated measures multivariate analyses were used to compare the smaller follicle sizes with the lead follicle.


METHODS
Oocyte maturation, fertilization, and embryo quality.


RESULTS
Compared with the lead follicular group (>18 mm), the odds of a mature oocyte from a 16 to 18 mm size follicle were 37% and declined progressively with each size. The odds of fertilization of oocytes from follicles 16 to 18 mm in size was 28% less than the lead group and decreased with each size. The rate of polyspermy with conventional insemination was increased for the smaller follicular groups (adjusted odds ratio = 2.37). Follicle size did not predict embryo cell number, but embryos from smaller follicles had a statistically significantly higher fragmentation compared with the lead group.


CONCLUSIONS
The lead follicular group was most likely to have a mature oocyte that was capable of fertilization and best suited for development into a high-quality embryo. The smaller follicles were capable of producing metaphase II oocytes that could fertilize, but at rates approaching only 60% that of the lead follicular group.
Rosen
Mitchell P
MP
Center for Reproductive Health, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, California 94115, USA.
Shen
Shehua
S
Dobson
Anthony T
AT
Rinaudo
Paolo F
PF
McCulloch
Charles E
CE
Cedars
Marcelle I
MI
D000328:Adult; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D007246:Infertility / Q000473:pathology* / Q000628:therapy*; D009865:Oocytes / Q000166:cytology*; D006080:Ovarian Follicle / Q000473:pathology*; D010062:Ovulation Induction; D011247:Pregnancy