Relationship between gonadotropin releasing hormone agonist dosage and in vitro fertilization outcome.

A prospective study in 132 women undergoing in vitro fertilization was performed in order to assess whether lower doses of gonadotropin releasing hormone agonists (GnRH-a) may ensure adequate oocyte retrieval and pregnancy rate, without pituitary oversuppression. Forty-five patients received subcutaneous tryptorelin depot (Decapeptyl 3.75, IPSEN SpA), 41 received subcutaneous tryptorelin acetate daily (Decapeptyl 0.1 mg, IPSEN SpA) and 46 received 0.05 mg tryptorelin acetate daily from day 21 of the cycle. From day 3 of the new cycle, if the estradiol levels were < 30 pg/ml, patients received two or three ampules of gonadotropin daily. In the group receiving subcutaneous tryptorelin acetate depot, the mean number of total gonadotropin ampules was significantly higher (p < 0.05), otherwise estradiol levels and the number of oocytes retrieved, fertilized and cleaved were significantly lower (p < 0.05). Pituitary oversuppression induced by GnRH-a causes an increase in the gonadotropin requirement for assisted reproductive techniques (ART) and a reduction in the number of oocytes retrieved and fertilized. There is a high risk of oversuppression in normal-weight or underweight women, because there is greater bioavailability of the peptide, hence elevated circulating levels of GnRH-a. Thus, ovarian stimulation in ART cycles depends on many factors, not least the identification of the best GnRH-a dose.