Embryo quality in natural versus stimulated IVF cycles

Area of Science:

• Reproductive Medicine
• In Vitro Fertilization (IVF)
• Embryology

Background:

• The effect of controlled ovarian stimulation (COS) on oocyte and embryo quality is debated.
• This study directly compares embryo quality in natural versus stimulated cycles within the same patients.

Purpose of the Study:

• To compare embryo quality between natural and stimulated cycles in patients undergoing IVF.
• To investigate if exogenous gonadotropins used in COS affect subsequent embryo development and quality.

Main Methods:

• Retrospective analysis of patients with regular cycles undergoing IVF with COS (rFSH, GnRH agonist protocol).
• Comparison of embryo quality (cleavage stage, cell number, fragmentation) between fresh embryos from stimulated cycles and embryos from modified natural cycles (mFER).

Main Results:

• No significant difference in embryo cleavage rates (70.4% stimulated vs. 66.4% natural).
• Similar distribution of cleavage stages and embryo cell numbers (>=4 cells) after 2 days of culture.
• No significant difference in embryo fragmentation (<10%) at day 2 transfer (61% stimulated vs. 69% natural).

Conclusions:

• Controlled ovarian stimulation (COS) using exogenous gonadotropins does not appear to negatively impact embryo cleavage capacity or quality.
• Embryo quality assessment showed no significant differences between stimulated and natural cycles in the same patient cohort.