The Princess of Wales joked she still sees Prince Louis as her baby - even though she recognises he is a "big boy now".
Kate made a surprise visit to the maternity unit at the Royal Surrey County Hospital in Guildford earlier today, where she stopped to speak to hundreds of members of staff and the public. And while there, she reminisced about her own three babies ( Prince George, Princess Charlotte and Louis), their scrunched-up newborn days and tiny fingernails. She joked that she still considered four-year-old Louis her baby until she saw a real infant and remembered he is, without doubt, a "big boy now".
Meeting baby Giles Talbot-Erasus, she remarked: "I keep thinking Louis is a baby but he's a big boy now. It just feels like yesterday."
Admiring his mittens, which covered long fingernails, she added of the newborn's scrunched-up pose: "George was so huddled up too, he spent quite a few days like that."
Speaking to second-time parents Hannah and Luke Culverwell who had a two-day-old baby boy and his older brother at nursery, she heard how the toddler currently had a little bump on the head just in time for the family photographs.
"They all get them," she reassured them, smiling. "They just seem to pick up these cuts and bumps, it's part and parcel of it."
Kate also met with new mum Szilvia Novak and her baby daughter Bianca, who was born six weeks premature. And sweet images show the princess chatting to Ms Novak while holding tiny Bianca in her arms.
It came after the new mum, originally from Budapest in Hungary, asked the princess if she would like to hold the baby while the pair were talking in the hospital’s Special Baby Care Unit.
Kate replied: "Am I allowed to?" before a member of staff helped Ms Novak pass the baby to Kate.
As she cradled Bianca in her arms, Kate said: "She's very sweet."
She then returned the baby to Ms Novak before continuing her tour of the hospital.
Afterwards, Ms Novak said: "I asked her if she wanted to hold her and she opted for it. I can't blame her. (Bianca) is cute.
"(The princess) was lovely to speak to. I was really impressed. You don't feel like you have classes between you. It's really nice."
Kate had chosen the hospital herself for an engagement in recognition of its outstanding status in maternity care and a recent UNICEF Baby Friendly Initiative Gold Award for its work to support infant feeding and parent-infant relationships.
In particular, it is one of few hospitals with facilities to allow mothers to stay with their babies while in the special care baby unit (SCBU) and provides continuity of care for mothers throughout their pregnancies with the same midwife.
The Princess also visited the Jasmine Team, which provides mental health support, as well as heard how SCBU was supporting families.
She spent time talking to Chiara Hale, a teenage mother to Maeve who was born in June, and Ria Clarke-Rice who used the mental health services at the hospital.
The Princess asked staff a series of questions about how and when they offered mental health support to pregnant women and mothers, how receptive people were to it, and how a perceived stigma is changing.
"So many women don't reach out for help because they don't realise what they're going through until much further down the line," she said.
"That's why this wraparound support is so important, not just from a medical team but also family and friends.
"Being able to open the conversation up for mothers to prioritise and take care of themselves.
"So often you think 'I don't have time' or 'my children come first' but actually if you can be the best person in yourself, you are supporting your child."
The visit was Kate’s first major solo engagement since being made the Princess of Wales by King Charles, the day after the death of the late Queen.
Early years care will continue to be a major focus in her role as the Princess of Wales, and the visit is part of a series by Kate and her husband Prince William this week to showcase their continuing key interests.
