This is a naturally occurring opiate. Beta-endorphin has properties similar to Morphine, Pethidine and heroin, and has been shown to work on the same receptors of the brain. Like oxytocin, beta-endorphin is secreted from the pituitary gland, and high levels are present during sex, pregnancy, birth and breastfeeding. Beta-endorphin is also a stress hormone, released under conditions of duress and pain, when it acts as an analgesic and, like other stress hormones, suppresses the immune system.
Like the addictive opiates, Beta-endorphin induces feelings of pleasure and euphoria. There are high levels in pregnancy and the levels increase throughout labour,(8) when levels of beta-endorphin and corticotrophin (another stress hormone) reach those found in male endurance athletes during maximal exercise on a treadmill.(9) Such high levels help the labouring woman to transmute pain and enter the altered state of consciousness that characterizes and undisturbed birth.
Beta-endorphin has complex relationships with other hormonal systems, that are not completely understood.(10) In labour, high levels will ingibit oxytocin release. It makes sense that when pain or stress levels are very high, contractions will slow, thus “rationing labour according to both physiological and psychological stress”.(11)
Beta-endorphin also facilitates the release orf prolactin during labour,(12) which prepares the breasts for lactation and also aids in the final stages of lung maturation for the baby(13). Beta-endorphin is also important in breastfeeding. Levels peak in the mother at 20 minutes,(14) and it is also present in breastmilk,(15) inducing pleasure and mutual dependency for both mother and baby in their ongoing relationship.