The Duchess of Cambridge has said there is "a massive gap" in support given to parents after the first few months of a child's life until they start school.
It was something she felt too as a new mum, the duchess told BBC Breakfast.
Catherine was speaking as part of the launch of the BBC's Tiny Happy People initiative for children aged 0-4.
It aims to help parents develop their children's language skills with simple activities including free online videos and quizzes.
During the interview, the duchess also spoke about the difficulties of life in lockdown for so many, but said one of the "silver linings" might be that we revalue how important our relationships are.
'Gold dust for families'
The duchess has long championed the importance of improving early years support for children. Earlier this year, she ran a nationwide survey to "spark a national conversation" and help create change for future generations.
At the heart of the BBC's five-year Tiny Happy People initiative is a simple message - talk to children from as early an age as possible.
It includes a range of online activities including parenting tips, films, articles and quizzes launched to help parents and carers develop the communication skills of their young children, right from the start of pregnancy.
The scheme was initially launched in Manchester last October, and Catherine has been involved for several months.
She recently met families at Sandringham, the Queen's estate in Norfolk, to hear about how they had found the activities. One of the parents she spoke with, Ryan, said they had helped him to identify that his eight-month-old daughter Mia has five different cries.
"He's learned a huge amount from Tiny Happy People," the duchess said, speaking to the BBC in the grounds of Sandringham.
"It's information like that I wish I had had as a first time mum, it's gold dust really for families to be given those tips and tools to be able to use, particularly in those first five years."
She said parents receive help from midwives and health visitors after a baby is born, but there's a gap before they start school.
Research by the National Literacy Trust shows that once children start behind, they stay behind, affecting performance in school, job prospects and even life expectancy.
And other Department for Education research shows more than one in four children (27%) in England does not reach the necessary level of literacy development - meaning language, communication and literacy skills - by the time they start primary school, rising to more than one in three (42%) in deprived areas.
'So proud of BBC commitment'
The free films, articles and quizzes explain the science behind baby brain development.
They include fun activities to do with both babies and toddlers to support language development and parent wellbeing, along with tips for new and soon-to-be parents.
"We couldn't be more proud of the part we're playing in this amazing partnership," said Tony Hall, the director general of the BBC.
"Growing up happy and healthy is the greatest gift we can give to any child. This campaign embodies our mission to inform, educate and entertain. The BBC has created hundreds of videos and written content that we hope will make a real difference."
James Purnell, the director of BBC Radio and Education, added: "Early years language provides the foundation for all aspects of a child's life - right into adulthood.
"Tiny Happy People is a major, long-term education commitment from the BBC to help close the under-fives language and communication gap, and help give kids the best chance in life. We're all so proud of it and look forward to seeing parents and carers from across the UK using the materials."
The duchess helped in the character and background development for two animations on parenting, which are now available on the Tiny Happy People website, about making eye contact with babies and singing to babies.
Also supporting the initiative are a number of celebrities who are using the activities to build their own infants' communication skills, including soap stars Jennie McAlpine and Kieron Richardson, singer and farmer JB Gill, former Love Islanders Jess and Dom Lever, BBC Three presenter Annie Price, and Louise Pentland, who was voted the UK's favourite mum influencer last year.
Catherine and her husband, the Duke of Cambridge, have three children - Prince George, Princess Charlotte, and Prince Louis.
The Royal Foundation website says the duchess believes "many of society's greatest social and health challenges" could be "mitigated or entirely avoided" if young children are given "the right support".
The interview with the duchess is being broadcast on BBC Breakfast on Tuesday 14 July. Visit the Tiny Happy People website here.