Follicular Fluid Steroid Hormone Levels Are Associated With Fertilization Outcome After Intracytoplasmic Sperm Injection

In women undergoing ovarian hyperstimulation during in vitro fertilization, follicular aspiration does not always result in a healthy fertile egg. Despite nuclear maturation, some oocytes degenerate with intracytoplasmic sperm injection (ICSI) or fail to fertilize. Several investigators have suggested that there may be differences with ICSI in concentrations of follicular fluid hormone levels in individual follicular aspirates between oocytes that fertilize successfully, those failing to fertilize, and those that degenerate. A recent study reported no differences between steroid concentrations in follicular fluid from follicles yielding a healthy egg and those failing to fertilize. This and other studies attempting to establish correlations between follicular fluid hormone levels and oocyte competence have been hampered by design and methodologic deficiencies. The aim of this prospective cohort study was to investigate the role of the follicular hormonal milieu in determining oocyte competence and fertilization outcome among in vitro fertilization patients undergoing ovarian hyperstimulation and ICSI. Follicular size and growth was monitored by transvaginal ultrasound-guided aspiration of the hyperstimulated ovary. Each follicle was aspirated and collected, and ICSI was performed on individually cultured oocytes. Chemiluminescent immunoassays were used to determine levels of follicular fluid gonadotropin and steroid hormones. The primary study outcome measure was oocyte fertilization outcome with ICSI. Compared with oocytes that degenerated with ICSI, those that fertilized normally were retrieved from follicles with significantly higher estradiol and testosterone concentrations (adjusted odds ratio [aOR], 1.28; 95% confidence interval [CI], 1.05–1.56; P = 0.01 and aOR, 1.35; 95% CI, 1.05–1.73; P = 0.02, respectively). Moreover, oocytes that fertilized normally with ICSI came from follicles with significantly higher concentrations of estradiol (aOR, 1.14; 95% CI, 1.00–1.20; P = 0.05) and progesterone (aOR, 1.09; 95% CI, 1.02–1.17; P = 0.01) compared with those that failed to fertilize. These findings suggest that the hormonal profile of the follicular fluid may play a key role in determining which oocytes will develop normally and which will degenerate or fail to fertilize. The data suggest that higher follicular fluid estradiol may be a marker for oocytes likely to fertilize normally following ICSI.