Taking to Twitter to share the fresh-faced snap, the 46-year-old presenter explained that the mark an audience member had referred to on social media was actually pigmentation which was brought on by pregnancy.
'This is the 'birthmark' on my face - actually chloasma - pigmentation brought on in my second pregnancy of which I'm actually v proud!' she wrote to her 454k followers, setting the record straight.
This is the 'birthmark' on my face - actually chloasma - pigmentation brought on in my second pregnancy of which I'm actually v proud! pic.twitter.com/UtTOezTDiq— Susanna Reid (@susannareid100) October 6, 2017
The discussion was sparked after a segment on the morning TV programme about airbrushed images, where Susanna commented: 'You don't look like the girl in the magazine because the girl in the magazine doesn't look like the girl in the magazine'.
The quote was then posted by the Good Morning Britain Twitter account, along with two images of Susanna with and without make-up, much to the praise of many.
However, the pics were also criticised, in particular by one user who wrote: 'I would say well done if she had shown the birthmark like skin blemish on her right cheek instead of angling the photo so you can't see it.'
Fans have since applauded Susanna, who has three sons, for her empowering response to the negative comment, with several sharing stories of their own experiences of chloasma.
'I have it from being pregnant with my son too... I also wear mine with pride x,' one wrote, followed by a second who said: 'I have 2 on my face which people are always trying to wipe off! I always tell them it's where God left his fingerprints 😉'
'It's heart shaped! How wonderful!' a third exclaimed. 'It's part of you so it's beautiful, loveable and perfect as with all of us.'