Background: Despite the clinical outcomes of ovarian stimulation with either GnRH-agonist or GnRH-antagonist analogues for in vitro fertilization (IVF) being well analysed, the effect of analogues on oocyte/embryo quality and embryo development is still not known in detail. The aim of this case-control study was to compare the efficacy of a multiple-dose GnRH antagonist protocol with that of the GnRH agonist long protocol with a view to oocyte and embryo quality, embryo development and IVF treatment outcome.

The effect of oocyte dysmorphism on further embryo development is controversial. It is generally accepted that serious oocyte abnormalities can have a negative effect on further fertilization and development. A couple reported to the clinic following 2 years of infertility and underwent five IVF/intracytoplasmic sperm injection treatments due to severe male factor infertility. A total of 42 oocytes were collected. The majority of the oocytes showed at least one large, fluid-filled and centrally located cytoplasmic vacuole and unusually thin zona pellucida. Only seven oocytes showed normal fertilization. The first four IVF treatments did not result in pregnancy. In the fifth IVF treatment, three poor-quality vacuolized embryos were transferred. A singleton pregnancy was detected. A baby girl was born at term who required surgery because of a double left kidney and ureter. This case report demonstrates that serious oocyte abnormalities can be a recurrent phenomenon in the same patient. However, the presence of a large vacuole does not completely block the fertilization process and this abnormal cohort of oocytes can still result in normal embryo development and a viable offspring. Rigorous prenatal care and follow-up should be carried out following the transfer of embryos developed from dysmorphic oocytes.