The launch comes after the charity found that 74% of mums and dads said that their baby not breathing is the first aid emergency they “fear most”.
In the survey of 2,000 parents, they also found only one in four knew what to do if their baby stopped breathing.
The babygrows will be available in Tesco stores on Thursday 13 October, with an optional donation going to St John Ambulance.
“We hope the worst will never happen but the babygrow, and our online video, shows parents what to do in a very clear and simple way,” said Sue Killen, CEO of St John Ambulance.
The garment features a reminder from the nursery rhyme ‘Humpty Dumpty’ of the five puffs and 30 pumps, followed by two puffs and 30 pumps parents need to give their baby if they stop breathing.
There are clear instructions on the collar of the babygrow and on the tag to help parents remember what to do.
St John’s Ambulance said the babygrow will “strengthen parents’ first aid knowledge each time it’s worn, washed and handled”.
Michelle McEttrick, group brand director, Tesco, added: “We’re delighted to be supporting St John Ambulance in bringing this lifesaving lesson to parents - a perfect example of Every Little Helps.”
Mum Alex McHugh, aged 33 from Wigan, thinks the babygrow is a great idea.
McHugh saved her son Joel’s life after he stopped breathing at just seven weeks old when the family were getting into the car after the school run.
McHugh said she only knew what to do after she had seen a St John Ambulance baby CPR advert just a day prior to the incident.
“To have CPR advice on an everyday item like a babygrow will be so helpful to parents and will highlight the importance of learning baby first aid so they can be prepared in an emergency like I was,” she said.
“It’s every parent’s worst nightmare that their child will stop breathing and this easy-to-understand advice can be the difference between a life lost and a life saved.”
Participating stores giving out the babygrows can be found on Tesco’s store locator.