Clinical meaning
Infertility is defined as the inability to conceive after 12 months of regular unprotected intercourse in women under 35, or after 6 months in women 35 and older. It affects approximately 10-15% of couples and may result from female factors (35-40%), male factors (30-35%), combined factors (20%), or unexplained etiology (10-15%). The NP must understand the complex interplay of hormonal, anatomical, and gamete-related factors to conduct a systematic infertility evaluation. Female reproductive physiology centers on the hypothalamic-pituitary-ovarian (HPO) axis. The hypothalamus secretes gonadotropin-releasing hormone (GnRH) in a pulsatile fashion, stimulating the anterior pituitary to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH drives follicular recruitment and growth in the ovaries during the follicular phase (days 1-14). Granulosa cells of developing follicles produce estradiol, which provides negative feedback to the hypothalamus and pituitary, suppressing FSH and allowing selection of a dominant follicle. At mid-cycle, a critical threshold of estradiol triggers a positive feedback surge of LH, which induces ovulation approximately 36 hours later. The ruptured follicle transforms into the corpus luteum, which secretes progesterone to prepare the endometrium for implantation....