Kate Middleton has spoken candidly about her struggle to adjust to life as the caregiver for two small children, revealing that she has found motherhood more difficult than people might assume.

The Duchess of Cambridge was attending a screening of the Best Beginnings series (a partner of her mental health charity Heads Together) when she made the unexpectedly frank comments about the pressures of parenting.

Middleton, 35, said that the short films highlight “how vital it is to be open about our mental health, especially in the early years of parenthood.

“Personally, becoming a mother has become such a rewarding and wonderful experience,” she said. “However, at times it has also been a huge challenge.”

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Middleton’s children with Prince William, Prince George and Princess Charlotte, are aged three and 22 months respectively. She said that while she knows she “has support at home that most mothers do not”, she still occasionally finds motherhood difficult.

“Nothing can really prepare you for the sheer, overwhelming experience of what it means to become a mother,” Middleton said. “It is full of complex emotions of joy, exhaustion, love and worry all mixed together.

“Your fundamental identity changes overnight,” she continued. “You go from thinking of yourself as primarily an individual, to suddenly being a mother first and foremost.”

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These feelings are universal, Middleton said – but she stressed that there is no rule book and no right way to be a perfect mother.  “You just have to make it up, and do the very best you can to care for your family. For many mothers, myself included, this can at times lead to a lack of confidence and feelings of ignorance.”

The so-called “baby blues” – feeling low, tearful or anxious immediately after giving birth – is such a common phenomenon that it’s considered normal, according to NHS Choices. However, between 10 and 20% of women in the UK develop a mental illness during pregnancy or within the first year of having a baby, with conditions ranging from postnatal depression to obsessive compulsive disorder and psychosis.

Many women, Middleton said, will go through these struggles in silence, in part because of the stigma that is still attached to mental health issues. “Some of this fear is about the pressure to be a perfect parent,” she said. “Pretending we’re all coping perfectly and loving every minute of it.

“It is right to talk about motherhood as a wonderful thing, but we also need to talk about its stresses and strains,” the Duchess of Cambridge continued. “It’s okay not to find it easy, and asking for help should not be seen as a sign of weakness.”

She concluded: “Our children need us to look after ourselves and get the support we need.”

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While it has historically been unusual for members of the Royal Family to talk about mental health, Middleton – along with husband Prince William and brother-in-law Prince Harry – has chosen it as one of her key causes.

In January, the royals criticised the traditional British mentality of “keep quiet and carry on” as they launched their Heads Together campaign.

“There are times when, whoever we are, it is hard to cope with challenges – and when that happens being open and honest and asking for help is life-changing,” said William, the Duke of Cambridge.

He added: “It is no exaggeration to say that conversations – simple conversations – can be life-changing: in a workplace, in your kitchen at home, with a friend, family member or colleague.

“And that’s what Catherine, Harry and I want to do – we want more people to be having those conversations.”

Images: Rex Features