Duchess of Cambridge insists no mother is "immune to experiencing anxiety and depression".
The 40-year-old duchess has been announced as a patron of the Maternal Mental Health Alliance, and she's stressed the importance of proving the "right support at the right time" to mothers across the UK.
In a video message, the duchess - who has Prince George, eight, Princess Charlotte, seven, and Prince Louis, four, with Prince William - said: "Around 20 percent of women in the UK are reported to experience perinatal mental illness. Sadly, we also know that many more are suffering in silence. No one is immune to experiencing anxiety and depression during this time.
"It is crucial, therefore, that all those who might be struggling are given the right support at the right time, so that they’re able to share these feelings without fear of judgement and can access the information, care and support they need to recover."
The duchess - who married Prince William in 2011 - feels "proud" to have become a patron of the Maternal Mental Health Alliance, which provides care and support to women and families affected by mental health issues.
But she also acknowledged there's still much more that can be done to support mothers.
She said: "Much of this vital work has been led by the Maternal Mental Health Alliance, a fantastic organisation of which I am extremely proud to become patron of today.
"There is plenty more to be done. And it’s down to each and every one of us to support parents and carers, and all those who are raising children today.
"Because by ensuring that the next generation of children can thrive, we can help to build a stronger, healthier and more nurturing society which benefits us all."