Obviously feeling romantic on 14 February, the Olympic athlete took to Instagram to share the news.
'HAPPY VALENTINES DAY! ❤️👨👨👦❤️,' said Tom.
In the snap that the diver used to accompany his simple but sweet message, the duo smile while holding up a picture of the scan.
Tom's film-maker husband also posted a photo on the social networking site.
He captioned the equally adorable image: 'A very happy #ValentinesDay from ours to yours.'
Fans were undoubtedly thrilled for Tom and Dustin, with many gushing over the pair's revelation.
'Congratulations!! Happy Valentine’s Day you’ll both make such amazing parents,' said one.
Another added: 'Wow 1000 times congratulations to you two! 😭 - so happy and excited for you, that's one lucky baby 👶🏼💕.'
And Tom's announcement clearly left one of his 1.9 million followers feeling very emotional.
'I'm actually crying I am so happy happy for you two,' they tearfully exclaimed.
Tom met the 43-year-old American in 2013 and they tied knot in a romantic ceremony at Bovey Castle in Devon last year.
A few days after saying 'I do', Tom confirmed the union online.
'On 6th May 2017, I married the love of my life, @dlanceblack ❤️ We shared the day with 120 of our closest friends and family, from Texarkana to Plymouth' he said.
Thank you to everyone who made this weekend the most special weekend of our lives!'
Just a few months after their big day, Tom, 23, revealed that he and Dustin were already thinking about kids.
'Lance and I definitely want a family in the future - who knows when,' he told the Belfast Telegraph.
'We're both lucky to have supportive families and we want to share that with our own children.'