The cycling champion, who has won six Olympic golds, tweeted two pictures side by side, one showing his son, Callum David Robert Hoy, when he was born on October 15, and another showing Callum sleeping peacefully on his due date, December 27.
"Today was Callum's due date, but he arrived 11 weeks early," wrote Sir Chris. "Amazing how far he's come since then, we're so thankful."
Chris's wife of four years, Sarra Hoy retweeted the message, adding: "Our miracle".
Today was Callum's due date, but he arrived 11weeks early. Amazing how far he's come since then, we're so thankful. pic.twitter.com/1sbfrpot2j
- Chris Hoy (@chrishoy) December 27, 2014
Chris, who was the GB flag carrier in the 2012 Olympics opening ceremony, and his wife Sarra, 33, took Callum home from hospital on December 5, three weeks after he was born.
Speaking to Parentdish before Callum was born, Chris said that he was glad that he had been able to retire from competition before starting a family.
"We both wanted children, but I was aware about it being the right time," he said. "I don't know how athletes do it when they are still competing - both things take all your energy and time.
"I wanted to commit 100Slideshow-164878%