A four-week-old baby died after his mother took him to a nightclub before drunkenly falling asleep on him, a court has heard.
Marina Tilby, 26, was seen repeatedly throwing and catching her son Darian while clubbing, before taking him back to a caravan with two men she had met.
He was found unresponsive lying next to Tilby in New Quay, Ceredigion, in the early hours of 31 March, 2017.
Tilby admitted wilful neglect and was jailed for two years and four months.
Judge Paul Thomas labelled the incident a "dreadful case of maternal selfishness".
Swansea Crown Court heard Tilby was so drunk she could not be woken by her sister, who had also stayed at the caravan, for an hour and 15 minutes.
Meanwhile, Darian, who was unresponsive with blood in his mouth, had been taken to Bronglais Hospital in Aberystwyth, where he later died.
Prosecutor Catherine Richards said Darian had died after Tilby, of Llwyncelyn, Ceredigion, fell asleep on him.
But Judge Thomas expressed his "unease" that medical evidence could not prove this had caused his death or rule out other possibilities.
Dyfed Thomas, defending Tilby, said she had been diagnosed with depression since his death and had "clearly suffered".
"She wishes to express to the court, the baby's father and her own family her own remorse and feeling of guilt from that night," he said.
"Her grief will fill her for the absence of her child for the rest of her days."
Judge Thomas added: "It is a mother's responsibility, a mother's duty and her natural instinct to put the care and safety of her four-week-old child above all else.
"You completely ignored that duty so you could get extremely drunk on a night-out."