Kate Middleton is stylish with Prince William and Prince Harry at Rugby match

She's been out of the spotlight on maternity leave for months, but Kate Middleton has certainly returned in style. After making her daytime post-baby debut this week, the Duchess of Cambridge was just as picture perfect in a royal blue Reiss coat as she stepped out for the opening ceremony of the Rugby World Cup – her first night out since the May birth of baby Princess Charlotte.

CLICK BELOW FOR MORE OF KATE'S ANIMATED RUGBY OUTING

Kate was all smiles at the match Photo: AFP/Getty Images

Along with thousands of fans, 33-year-old Kate joined Prince William, Prince Harry and Prime Minister David Cameron at Twickenham rugby stadium where hosts England played Fiji.

It is the perfect return to social life for the royal mom, who is as passionate about sports as her husband. William is the president of international soccer organization FIFA, and of course Harry is the founder of the Invictus Games for injured veterans – and all three were ambassadors at the 2012 London Olympics.

Kate enjoyed a date night of sorts with William Photo: AFP/Getty Images

The start to the tournament marked the second engagement of the week for Kate, who visited the Anna Freud Centre on Thursday to show her support for their work with children's mental health. With a new hairstyle and wearing a $1,595 Ralph Lauren dress, the mother of two made an elegant return to work.

The engagement was a chance for her to show where she plans to focus her efforts in the coming months and support the vital work done by a family friend. The trustee chairman is Michael Samuel, husband of Prince George's godmother Julia Samuel – who in turn who was a friend of Princess Diana.

Prince Harry joined his brother and sister-in-law Photo: AFP/Getty Images

Little George and Charlotte had probably been left behind in the capable hands of royal supernanny Maria Teresa Turrion Borrallo. Kate has kept a low profile since giving birth on May 2, taking time out from public life at the Cambridges' country retreat Anmer Hall.

She and her husband did attend the America's Cup World Series in Portsmouth, England, in July, where Kate appeared in high spirits despite the race being called off. More recently, the Cambridges traveled to Balmoral in Scotland, to help Queen Elizabeth celebrate her achievement in becoming Britain's longest reigning monarch.

For more of the latest celebrity and royal news follow us @HelloMagUS on Twitter, Pinterest and like us on Facebook.