The Duchess of Cambridge met academics at the innovative King's College London's Maurice Wohl Clinical Neuroscience Institute and learned about the long lasting impact untreated mental health problems in new mothers can have on the family.
Kate, who is pregnant with her third child, visited a laboratory at the institute and received a briefing on its work in perinatal research.
Kate later visited the Perinatal Service in the Mother and Baby unit at Bethlem Royal Hospital.
Meanwhile, across the country, Prince Charles and the Duchess of Cornwall also needed their umbrellas, on a tour of Cheshire.
Camilla was meeting HMP Styal inmates benefiting from work-based training and education programmes.