Control of growth hormone secretion during the postpartum period

The postpartum period is characterized by high levels of circulating steroids which condition hypothalamo-pituitary activities. In pregnancy growth hormone (GH) levels are greatly increased and lack pulsatility. In order to investigate the behavior of GH during the postpartum period, the GH response to GH-releasing hormone stimulation (50 and 100 micrograms), to amphetamine, a dopamine receptor agonist, and to FK 33-824, an opiate receptor agonist, was investigated in women during the first 5 days after delivery. In all groups GH responses were significantly lower (p less than 0.01) than in normal women studied during the early follicular phase. FK-33-824-induced GH release was similar in postpartum and control women. These results demonstrate reduced pituitary GH response to GH-releasing hormone and to amphetamine in women during the postpartum period, confirming the peculiarity of the hypothalamopituitary component.