There are only three events in your life that trigger oxytocin release: nipple stimulation (like when I'm breastfeeding),
labor (the oxytocin released during childbirth stimulates uterine contractions, which is why nipple stimulation might be suggested when
labor stalls, and
also explains why sometimes, after you breastfeed me, you feel an increased expulsion of lochia and maybe some cramping), and... orgasm!!