On June 7th Jean Cotterman wrote, in part, "I do not remember associating that [adoring] feeling with the let-down reflex... I have trouble with the new research that states, or at least implies this is 100% due to the effect of oxytocin. I remember reading a '50's Life magazine reprint from LLL that described a policeman with a pituitary tumor who felt very nurturing till it was removed, and of laboratory animals where the males would make nests and cuddle the young after being given prolactin shots. In light of that information, I decided that the surge of prolactin stimulated by each breastfeeding session must have been responsible for that feeling flooding over me each time." K Dettwyler (same date) replied "And it *is* clearly oxytocin that is responsible for that wonderful affectionate, loving feeling you have when you breastfeed. Read the work of Niles Newton. Prolactin levels return to their pre-pregnant/non-lactating levels within six months of birth, and are not associated with continued milk production, continued amenorrhea, or feelings of affiliation the way oxytocin is." (a) There is research supporting the position that prolactin causes "warm fuzzy" feelings. Riordan and Auerbach p100: "Prolactin reportedly has a relaxing effect, causing the breastfeeding woman to feel calm, even euphoric, during the feeding." Marie Davis, p90 in the _Core Curriculum for Lactation Consultant Practice_ (ed. Marsha Walker) cites this statement and also research by Lauwers and Shinskie 2000 to the effect that prolactin gives the mother "a feeling of yearning for her baby". (b) Baseline prolactin levels drop over several months, but not all the way to pre-pregnancy levels. Lawrence (5th ed.) p70: "Although it was initially reported that the high levels of prolactin measured in the first days and weeks of lactation dwindled to normal baseline by 6 months and showed no response to suckling stimulus, later studies clearly showed a different picture with more sensitive assays. Baseline does not drop to normal..." A graph on p 68 shows baseline levels for menstruating non-lactating women ranging from 8 to 14 ng/ml while the *baseline* levels for lactating women in the second half-year (i.e. after dropping from the very high levels of the early postpartum months) are from double to quadruple those levels, ranging from 30 to 40 ng/ml. Riordan & Auerbach p99 cite research saying levels of prolactin remain elevated above pre-pregnancy baseline levels "for as long as the mother breastfeeds, even if she breastfeeds for years". (c) There continues to be a crucial (though highly variable) differential between baseline levels and a suckling-induced surge in prolactin. Graphs on p69 of Lawrence clearly show prolactin surges in response to suckling which continue to (and past) 180 days. Lawrence p70 again: "further stimulus causes a doubling of levels over baseline at all stages of lactation through the second year." (d) This prolactin surge does appear to be associated with milk production: Hale, in recent discussions of pseudoephedrine's effects on lactation, reports that the drug has the dual effect of flattening the prolactin surge and approximately halving milk output. "The surge in prolactin over baseline levels is critical to milk production" (Lawrence p69). (e) Prolactin is associated with amenorrhea. On p100 Riordan & Auerbach say that higher prolactin levels occur in amenorrheic women than in those who are cycling and add that "[t]he role of prolactin in the delay of fertility is well known." Elise in pre-exam mode :-) *********************************************** The LACTNET mailing list is powered by L-Soft's renowned LISTSERV(R) list management software together with L-Soft's LSMTP(TM) mailer for lightning fast mail delivery. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html