Duchess Kate, who is thought to be around 12 weeks pregnant with her third child, has been suffering from the severe morning sickness hyperemesis gravidarum but has recovered sufficiently to undertake her first official duty since August 30.
The future Queen, who was too sick to accompany Prince George on his first day at school in early September, joined the Duke of Cambridge and Prince Harry to host a palace reception celebrating the contribution of those working in the mental health sector to mark World Mental Health Day.
William, Kate and Harry have spent the last year trying to encourage a national conversation about mental health, using with their Heads Together campaign to ask people to speak out about their psychological problems or be a sympathetic ear for others.