Oxytocin (IPA: /ˌɔk.sɪ.ˈtoʊ.sɪn/) (Greek, "quick birth") is a mammalian hormone that also acts as a neurotransmitter in the brain.
It is best known for its roles in female reproduction: it is released in large amounts after distension of the cervix and vagina during labor, and after stimulation of the nipples, facilitating birth and breastfeeding, respectively.