Little Luna Atkins had been at home only hours when she passed away in the bedroom tragedy in May last year.
Pathologists said her cause of death could not be determined and a coroner said co-sleeping with her parents Philippa Atkins, 34, and James Atkins, 35, was not to blame.
Recruitment company worker Philippa began breastfeeding Luna at around 9.30pm but both exhausted parents fell asleep.
Her mother woke four hours later to discover Luna was “unresponsive” and was declared dead by paramedics 50 minutes later.
Luna was born two weeks premature on May 9, 2020, by emergency Cesarean section.
She was discharged from the University Hospital of Wales two days later at around 5pm after doctors decided she was strong enough to return home.
But tragically Luna was declared dead at 2.20am at their home in Roath, Cardiff.
A post-mortem examination was carried out but the cause of death was recorded as “unascertained”.
South Wales Central Coroner David Regan said police had “no concerns” regarding Luna’s death and that the couple’s home was “clean and tidy” with “plenty of fresh food in the fridge”.
He said: “Her parents made the choice she could co-sleep with them – that is a choice clearly available to parents. It’s a choice they felt was in Luna’s best interests.
“Luna’s parents did not smoke, and there is no suggestion of any alcohol at all in the blood samples they provided.
“Luna appeared healthy and bright and was discharged home on May 11, 2020.
“She went to sleep in her parents bedroom, sleeping between them, that night.
“It seems to me there is absolutely no evidence at all that co-sleeping was contributive of Luna’s death.”
Mr Regan gave a conclusion of unascertained natural causes.
Philippa is now fundraising to help other children – and described Luna as “our beautiful baby” and “our perfect little girl”.
She said: “Luna has taught me life is too short and too precious! We owe it to her to fill the world with more music and more joy.
“So if you ever think you can’t, look up at the moon, and my baby will show you that the world is good and you are loved.
“I got to carry Luna for nine months, and hold her for nearly three days.
“I knew my daughter and she was good. She has given me the strength to believe in myself and strive to make the world a better place.
“Whatever you have been through, I am always here for you as you are there for me.
“As things start to go back to ‘normal’ let’s strive to make it better.
“Let’s laugh more and sing more. Let’s never forget the tragedies of the last few months, and let’s remember those we have lost in the best possible way.”
Keen runner Philippa is now planning a half marathon in honour of Luna and other children by raising money for the Martha’s Dancing Heart appeal and the Cardiff and Vale NHS Trust.