The One Show presenter shared a snap of herself in a stripy dress, pointing at her tummy, captioning the pic: 'The bump is gathering pace!!'
Fans were quick to compliment Alex on her changing figure, telling her that she's 'glowing'.
'Looking gorgeous hon! So excited for you both,' one commented, whilst a second added: 'You look so beautiful and blooming. We are so happy for you.'
Alex revealed that she was expecting her first child with husband Charlie Thompson back in September, taking to social media share the very happy news with her fans.
The pair made the announcement by posting an image of a cute baby grow with the words 'Coming Soon' printed on the front.
She wrote: 'Charlie and I are very happy to confirm that we're expecting a little baby in the new year. Absolutely delighted and feel very lucky that we're about to become parents.'
Charlie & I are very happy to confirm that we're expecting a baby in the new year. Feel so lucky that we're about to become parents. Xx— Alex Jones (@MissAlexjones) September 2, 2016
Once the cat was out of the bag, the 39-year-old star began to share more details, speaking about her morning sickness - or lack there of - while presenting.
Joking about hiding her bump, Alex said while hosting The One Show, 'Lots of you had guessed – I'd been trying to breathe in, but now the secret's out I can relax. And breathe out!'
Alex and husband Charlie
She told viewers that morning sickness wasn't affecting her so far and how wonderful being pregnant felt: 'I've had no sickness and no tiredness. I feel great'.
Since sharing the news Alex has been overwhelmed by love and support from fans. She tweeted thanking followers for all their kind words, writing: 'Overwhelmed by all your messages of congratulations and love. Such a warm feeling. A huge thank you from us both. Diolch. On cloud 9! Xx'.
Overwhelmed by all your messages of congratulations and love. Such a warm feeling. A huge thank you from us both. Diolch. On cloud 9! Xx— Alex Jones (@MissAlexjones) September 3, 2016
Fans have been over the moon for Alex, liking her baby announcement tweet nearly five thousand times and sharing messages such as, 'Congratulations Alex, you will be an amazing mother' and 'Oh my goodness, amazing news! Much happiness for the months ahead and the joy of meeting your little one in the new year'.
The pregnancy comes after Alex filmed a documentary on fertility, revealing her worries that she left having children until too late in life, particularly after discovering that her mum went through the menopause at the age of 43.
She said: 'That was a shock and nonetheless I have a five year window potentially to get this done.'
'As most girls I spent all of my teenage years, twenties, thirties, doing everything I could to avoid getting pregnant and then... a day arrives and then you go "gosh, maybe we should have a baby".'