Four new photographs have been released of Kate, the Duchess of Cambridge, following a trip to a UK hospital's maternity ward.
The images show the duchess during a days-long visit to Kingston Hospital's maternity unit in November, Kensington Palace said in a statement.
In a letter, released today, Duchess Kate praised the midwives and their colleagues in the lead-up to International Year of the Nurse and Midwife.
She wrote: "You are there for women at their most vulnerable; you witness strength, pain and unimaginable joy on a daily basis."
In the letter, the British royal described accompanying community midwives during their rounds and being welcomed into people's homes, as well as visiting hospital clinics and post-natal wards.
"I was continually struck by the compassion that those of you I spent time with showed, and the incredible work ethic you demonstrated on behalf of your entire profession - not only performing your rounds but working tirelessly through the night to support people that were at their most vulnerable," Duchess Kate wrote.
"You don't ask for praise or for recognition but instead unwaveringly continue your amazing work bringing new life into our world.
"You continue to demonstrate that despite your technical mastery and the advancement of modern medicine, it is the human to human relationships and simple acts of kindness that sometimes mean the most."