Falling estradiol levels as a result of intentional reduction in gonadotrophin dose are not associated with poor IVF outcomes, whereas spontaneously falling estradiol levels result in low clinical pregnancy rates.
BACKGROUND
Although estradiol levels remain an integral part of monitoring in most IVF programmes, the effect of falling estradiol on IVF outcome has not been adequately quantified. The objective of this study was to evaluate the effect of falling estradiol levels prior to hCG on IVF outcome.


METHODS
This was a retrospective cohort study carried out in a university-based fertility clinic. A total of 112 IVF patients in whom estradiol levels fell prior to the administration of hCG were matched for age and year of treatment with 112 control IVF patients. IVF outcomes including oocytes retrieved, fertilization rate, embryos for transfer, and pregnancy rates were compared between the groups.


RESULTS
Seventy per cent of women in the falling estradiol group experienced spontaneously falling estradiol levels. Spontaneously falling estradiol was associated with fewer oocytes retrieved (median 5 versus 8, P=0.001), increased rates of failed fertilization (18 versus 6%, P=0.018) and lower clinical pregnancy rates (12 versus 26%, P=0.012) compared to controls. Despite marked decreases in estradiol levels, IVF outcomes for patients whose estradiol levels fell as a result of deliberate protocol modification had similar fertilization and clinical pregnancy rates as controls.


CONCLUSIONS
Subtle (<10%) spontaneous decreases in estradiol levels are associated with very poor IVF outcomes.
Fisher
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S
Genesis Fertility Centre, 555 West 12th Avenue, Suite 550, Vancouver, British ColumbiaV5Z 3X7, Canada. sfisher@genesis-fertility.com
Grin
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A
Paltoo
A
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Shapiro
H M
HM
D000328:Adult; D016022:Case-Control Studies; D006063:Chorionic Gonadotropin / Q000008:administration & dosage*; D015331:Cohort Studies; D004958:Estradiol / Q000097:blood*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D007246:Infertility / Q000628:therapy; D008297:Male; D016471:Ovarian Hyperstimulation Syndrome / Q000517:prevention & control; D011085:Polycystic Ovary Syndrome / Q000628:therapy; D011247:Pregnancy; D011379:Prognosis; D012189:Retrospective Studies
D006063:Chorionic Gonadotropin; D004958:Estradiol