The female reproductive axis and its modifications during the post-partum period
Thalabard, J.C.
Journal of Biosocial Science 24(3): 289-300
1992
ISSN/ISBN: 0021-9320 PMID: 1634558 DOI: 10.1017/s0021932000019854Document Number: 321361
Several determinants each play a role in the total blockade of the hypothalamic generator (HTG)--the hypophysiotrophic drive to the gonadotrophes--in the 1st postpartum days. These may include extremely high circulating sexual steroids near delivery and possibly following delivery, dopamine and alpha receptor agonists, and opiates. Data on humans and primates indicate that several weeks after delivery limited estradiol secretion and suckling behavior could work together to support the unstable equilibrium represented by an inefficient HTG. Undernutrition could even strengthen this blockade. For example, it suppresses luteinizing hormone (LH) pulsality. In addition, administration of estradiol was more effective in suppressing LH pulsality in undernourished rats than it was in well nourished rats. The adrenal axis may also contribute to the reproductive effect of prolonged reduced food intake as evidenced by high plasma cortisol levels in humans and in laboratory animals. A disturbance of this active equilibrium can occur at any time which returns physiological processes back to menstrual cyclicity--the normal adult equilibrium state. Health practitioners could manage postpartum events better if the scientific and medical community understood the causes and mechanisms of these disruptions and the means by which the neuro-ovarian cascade is activated. Researchers may begin to understand these processes during lactation if they study the pubertal period.