I have one 'gut instinct' moment that I will never forget.
When my DS was about 4 months old, I put him down in his cot on his back to sleep (as advised) for the night. He was well and happy when I put him into his cot, he smiled at me and I walked out and shut the door behind me. About five minutes later I had this incredible urge to go back and check on him, despite the fact that I would never normally check on him so soon because it may wake him up.
I opened the door and all was quiet, with no movement like he was asleep, but my instinct made me turn on the light.
He was lying on his back in the cot, silently choking on his own vomit. His face was contorted and his eyes rolling back in his head.
I grabbed him, flung him over my arm, hit him hard on the back and the vomit expelled with great force out of his mouth and across the floor. He took in a couple of huge sucking breaths and then started screaming.
We raced him to the hospital and he had aspirated vomit but was back to normal within a few days. The doctors made it clear that if I hadn't checked on him, he likely would have died, silently choking to death in his cot.
I can still remember the feeling that overcame me and urged me to check on him. It felt like pure instinct. I've never had the feeling before or since.