Background: The aim of this study was to compare the effect of three different times of onset of luteal phase support on ongoing pregnancy rate in infertile patients undergoing treatment with GnRH down-regulated IVF and embryo transfer (IVF/ET).
Materials and methods: All consecutive eligible patients planned to undergo their first IVF treatment cycle were randomly allocated to receive vaginal progesterone as luteal support at three different time points, that is, after HCG administration for final oocyte maturation (HCG group), at the day of oocyte retrieval (OR group) or at the day of ET (ET group). The primary endpoint of this study was ongoing pregnancy rate.
Results: A total of 385 women were randomized, 130 were allocated to the HCG group, 128 to the OR group and 127 to the ET group. An ongoing pregnancy rate of 20.8% was found in the HCG group versus 22.7 and 23.6% in the OR group and ET group, respectively. The mean number and quality of the retrieved oocytes and the transferred embryos did not differ.
Conclusion: Based on this data, an 18% difference in ongoing pregnancy rate between the three different times of onset of luteal phase support in GnRH agonist down-regulated IVF/ET cycles can be refuted. Smaller clinically meaningful differences may be present.