Infertility
The inability to conceive after 12 months of unprotected intercourse. GnRH agonists and antagonists play key roles in assisted reproduction: antagonists (cetrorelix, ganirelix) prevent premature ovulation during IVF, while agonists can be used for pituitary suppression in controlled ovarian stimulation protocols.
Technical Context
Defined as failure to conceive after 12 months of regular unprotected intercourse (6 months if female partner >35 years). Affects approximately 10-15% of couples. Causes: female factors (ovulatory dysfunction ~25%, tubal disease ~20%, endometriosis ~10%, uterine factors ~5%), male factors (~30%), combined factors (~20%), and unexplained (~15%). Peptide drug roles in fertility: GnRH agonists (nafarelin, leuprolide, goserelin) for pituitary suppression in IVF protocols (preventing premature LH surge during controlled ovarian stimulation), GnRH antagonists (cetrorelix, ganirelix) for flexible suppression in IVF (started when follicles reach 14mm, preventing premature LH surge without the initial flare — shorter treatment duration than agonist protocols), and GnRH agonist trigger (single dose to induce LH surge for final oocyte maturation — lower OHSS risk than hCG trigger, particularly important in high-responder patients).