INFLUENCE OF LH/FSH RELEASING HORMONE (LRH) ON THE BASAL SECRETION OF GONADOTROPHINS IN RELATION TO PLASMA LEVELS OF OESTRADIOL, PROGESTERONE AND PROLACTIN DURING THE POST-PARTUM PERIOD IN LACTATING AND IN NON-LACTATING WOMEN

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Abstract
The pituitary responsiveness to LH[luteinizing hormone]/FSH [follicle stimulating hormone] releasing hormone (LRH) was studied in the puerperium in lactating and in non-lactating women. The response of both groups of patients to 25 .mu.g LRH i.v. was tested 8-10 days, 15-17 days, and 29-32 days after a normal delivery at full term. Basal levels of FSH were low during the first 10 days after delivery. A rise was then observed, and about 4 wk after delivery, levels above or in the upper normal range of a normal follicular phase were recorded. Levels were significantly higher in the lactating group. When compared with the normal follicular phase, the relative increase in FSH basal levels was higher than the increase in LH basal levels in both groups of patients. The period of non-responsiveness of the pituitary to LRH was of equal length in the 2 groups. In both groups the FSH response returned more rapidly than the LH response. About 2 wk after delivery a reverse pattern of gonadotropin response to LRH was seen with a FSH response that was greater than the LH response compared with what is generally observed in the various phases of the menstrual cycle in eumenorrheic women. This pattern was more pronounced in the lactating group about 4 wk after delivery. Estradiol levels were low and roughly equal on the 3 test occasions in each group, but in the non-lactating group there was a tendency to higher concentrations. Prolactin levels were highest about 1 wk after delivery and then showed a tendency to decrease, this was more pronounced in the non-lactating group. Progesterone levels were invariably low in both groups.