The Duchess of Cambridge shared an emotional hug with the midwife who helped deliver one of her children as they were reunited.
Kate spotted Professor Jacqueline Dunkley-Bent among a crowd of guests during a visit to the Royal College of Obstetricians and Gynaecologists (RCOG) in north-west London.
The duchess, who is expecting her third child, seemed delighted and embraced the midwife as they exchanged a few brief words.
Professor Dunkley-Bent is understood to have assisted with the delivery of one of Kate's children, and was photographed in uniform outside St Mary's Hospital in Paddington following the birth of Princess Charlotte.
As she left, Kate thanked RCOG president Lesley Regan and added: "It was so great to see Jacqui as well."
It was announced on Tuesday that Kate has become patron of RCOG and the Nursing Now campaign, which she will officially launch during a later visit to St Thomas' Hospital.
Kate, wearing a two-piece blue Jenny Packham dress and coat, met trainees and professionals during her visit to RCOG, which works to improve healthcare for women.
She watched with interest as trainees demonstrated how they would perform keyhole surgery and stitch up skin following a caesarean and congratulated those nearing the end of the training.
As she was shown around, Kate paused to observe a painting of the Queen opening the building in 1960.
Presenting Kate with a certificate to mark her patronage, Professor Regan said: "On behalf of everyone here present, I would like to extend our very best wishes for the birth of your third child.
"I'm confident that you will receive excellent care from the wonderful team at my own hospital, as indeed you received for the births of Prince George and Princess Charlotte.
"Thank you once again for visiting the college today, becoming our patron and for showing such passionate interest in our work.
"We look forward to a very long and fruitful relationship with you and your family."