Success of oocyte retrieval in modified natural cycle assisted reproductive techniques: a retrospective cohort study

Background This study investigates how clinical factors and hormonal levels affect oocyte retrieval in modified natural cycles, aiming to improve understanding and enhance treatment protocols.Methods A retrospective analysis of data from 306 women undergoing in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) at a fertility clinic (2018–2023) was conducted. Clinical factors and hormonal levels were analysed. Follicular development was monitored via ultrasound.Results Baseline comparisons between the oocyte retrieval and non-retrieval groups showed no significant differences in age, body mass index, infertility types, duration, associated conditions (e.g. tubal issues, ovulation disorders and endometriosis) or assisted reproductive methods (p > 0.05). After human chorionic gonadotropin (HCG) injection, both groups showed significant increases in progesterone, oestradiol and luteinising hormone levels (p < 0.0001). Before HCG injection, the retrieval group had significantly higher levels of progesterone, oestradiol and LH (p < 0.05), with oestradiol remaining higher afterward (p < 0.01). There were significant differences between the two groups on anti-Müllerian hormone levels (p ˂ 0.05). No significant differences were found in follicle-stimulating hormone, total testosterone, thyroid hormone levels and antral follicle count (p > 0.05).Conclusions In conclusion, the findings suggest that clinical factors do not impact oocyte retrieval in modified natural cycle assisted reproductive techniques. However, high hormone levels on the day of HCG injection in the study subjects may indicate a greater possibility of successful oocyte retrieval.