Chapter 7: Sex and Reproduction

In males, stress activates endogenous opioids that suppress gonadotropin-releasing hormone from the hypothalamus, reducing luteinizing hormone and follicle-stimulating hormone secretion from the pituitary gland and thereby lowering testosterone production and spermatogenesis. Both physical stressors such as trauma or infection and psychological stressors including social rank decline trigger these hormonal suppressions. Glucocorticoids further impair testicular responsiveness to pituitary signals, while elevated prolactin reduces overall pituitary sensitivity to reproductive signaling. Stress also disrupts sexual function by shifting autonomic nervous system balance toward sympathetic dominance, which interferes with the parasympathetic activation required for erections and can precipitate erectile dysfunction or premature ejaculation. The chapter notes that this pattern is not universal across species, using hyenas as an example where stress paradoxically triggers erectile responses as a dominance-submission display. In females, stress disrupts ovulation through multiple converging pathways: insufficient body fat from malnutrition or extreme exercise limits peripheral conversion of adrenal androgens to estrogen, endogenous opioids and prolactin inhibit pituitary and ovarian function, and glucocorticoids suppress progesterone production. These disruptions manifest as extended follicular phases, anovulatory cycles, or complete amenorrhea. Reduced estrogen and progesterone not only impair fertility but also accelerate bone loss and increase cardiovascular disease risk. The chapter discusses lactational amenorrhea as an example of how prolactin's natural reproductive suppression overlaps with stress hormone pathways, noting that intensive infant nursing in traditional societies extends birth spacing more substantially than modern breastfeeding practices. Stress diminishes sexual motivation in both sexes through reductions in gonadal steroids and adrenal androgens. The chapter further addresses stress-induced pregnancy complications, including increased miscarriage risk through catecholamine-mediated reductions in uterine perfusion and fetal oxygen supply, as well as the Bruce-Parkes effect demonstrating how stress hormones and social dominance signals can prevent implantation in rodents. Historical evidence from ancient medical texts through modern concentration camp studies illustrates that extreme stress severely compromises reproduction, though basic reproductive capacity often survives even under severe duress. Ultimately, the chapter argues that while acute stress appropriately prioritizes survival over reproduction, chronic modern psychological stress creates sustained hormonal imbalances that impair sexual function, fertility, and pregnancy outcomes.