Comparison of early versus late initiation of GnRH antagonist co-treatment for controlled ovarian stimulation in IVF: a randomized controlled trial

What is the impact of initiating GnRH antagonist co-treatment for in vitro fertilization (IVF) on cycle day (CD) 2 compared with CD 6 on live birth rate (LBR) per started cycle and on the cumulative live birth rate (CLBR)? Early initiation of GnRH antagonist does not appear to improve clinical outcomes of IVF compared with midfollicular initiation. During ovarian stimulation for IVF, GnRH antagonist co-treatment is usually administered from the midfollicular phase onwards. Earlier initiation may improve the follicular phase hormonal milieu and therefore overall clinical outcomes. This open-label, multicentre randomized controlled trial was conducted between September 2009 and July 2011. A web-based program was used for randomization and 617 IVF-intracytoplasmic sperm injection (ICSI) patients were included. Recombinant FSH (150225 IU) was administered daily from CD 2 onwards in both groups. The study group (CD2; n 308) started GnRH antagonist co-treatment on CD 2, whereas the control group (CD6; n 309) started on CD 6. There were no significant differences in clinical outcomes between the two groups. A non-significant trend towards a higher LBR per started cycle and CLBR was observed in the CD6 group compared with the CD2 group (LBR: 24.0 versus 21.5, P 0.5; CLBR: 29.9 versus 26.7, P 0.6). The study was terminated prematurely because no significant difference was observed in clinical outcomes after 617 inclusions. A much larger study population would be needed to detect a small significant difference in favour of either study arm, which raises the question of whether this would be relevant for clinical practice. The present study shows that the additional treatment burden and costs of starting GnRH antagonist on CD 2 instead of on CD 6 are not justified, as early initiation of GnRH antagonist does not improve LBRs.