When a woman breastfeeds, oxytocin levels rise even higher according to frequency of nursing, which in the first few weeks may occur as often as every hour or two. Breastfeeding is initiated in part by the hormone prolactin, which is released as estrogen and progesterone levels drop with delivery. Let-down of milk is caused by oxytocin's release, most directly by nipple stimulation. Generally, it's very pleasurable. There is a tingling in the breasts, a tightening as they fill, and a longing for release.
Women have the experience which can be directly correlated with an orgasm.
Sometimes, the accompanying uterine and vaginal contractions even lead to orgasm. The breast feeding process is not only a bond for mother and child but infact is a sexual experience in itself and is very stimulating for her. Studies have found that mood changes caused by breastfeeding are very much like those that occur with intercourse and orgasm. According to a research , lactating women have shown a suppression of adrenaline release and accompanying neurological activity in response to various kinds of trauma. The release of oxytocin through breastfeeding is something of a biological perk to help women buffer stress and make it through the physical challenges of this phase, such as sleep deprivation, hormonally based emotional changes, and sweeping physiological adjustments.