Effect of gonadotropin supplementation on oocyte maturation and mean oocyte diameter in rescue IVM: a prospective sibling-oocyte study

Rescue in vitro maturation (IVM) of immature oocytes retrieved during controlled ovarian stimulation (COS) offers an opportunity to increase the number of mature oocytes available for fertilization. However, the role of gonadotropin supplementation in standard culture media remains unclear. This prospective experimental study with a paired oocyte design evaluated the effects of FSH and LH supplementation on nuclear maturation and the potential for good-quality blastocyst development, assessed by mean oocyte diameter (MOD), in 104 immature oocytes (52 pairs) from 29 patients undergoing COS with a GnRH antagonist protocol. Sibling oocytes were allocated to standard fertilization medium (control) or medium supplemented with recombinant FSH (1.5 IU/mL) and LH (0.75 IU/mL) (intervention). The overall maturation rate was significantly higher in the intervention group (51.92% vs. 30.77%, p = 0.029), and this difference was confirmed by multivariable analysis (adjusted OR 3.28, 95% CI 1.25-8.64). GnRH agonist trigger was also independently associated with higher odds of maturation. No significant difference in MOD distribution toward the optimal range associated with good-quality blastocyst development was observed between groups. FSH and LH supplementation improves nuclear maturation during rescue IVM, though its effect on developmental potential requires further investigation in larger studies with downstream outcome assessments.