William looks 'pretty pleased with himself' claims body language expert as the Prince puts on protective display around pregnant Kate in New York

• Royal couple on whirlwind two-day visit to New York
• Kate is now five months pregnant with their second child 
• William kept a protective arm around his wife during their first two outings

It's her first official visit abroad since announcing her pregnancy. 

And a protective Prince William made sure he was alongside Kate every step of the way as the royal couple arrived in a chilly New York on their highly anticipated trip to the US. 

Never more than a foot away from her side, an attentive Duke of Cambridge kept an arm almost constantly on the small of Kate's back, guiding her through the crowds.

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Flattered: Kate and William beamed at the waiting crowds as William kept an arm firmly on Kate's waist

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Welcome! Prince William carefully ushered Kate into the Carlyle Hotel at 5.46pm on Sunday night

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Embrace: Kate's pregnant tummy was visible in her deep purple coat as William put his arm around her

Judi James, a body language expert, reveals that as well as a gesture of concern and chivalry, the prince's actions show he is 'pretty pleased with himself', showing 'protective alpha signalling'.

She told MailOnline: 'Impending fatherhood has a habit of making subtle changes to a guy's body language, and with his second child on the way William is no exception.

'There's a strong whiff of protective alpha signaling here, with his chest pat and hand-rubbing suggesting he's pretty pleased with himself right now, and he takes the role of the "advanced party" in these poses, climbing out of the car first and rushing off to meet and greet while Kate catches up in his wake.

'When they connect though there is a raft of mutual signals that are new to the couple's repertoire. William's arm is placed protectively around his wife's waist but she mirrors the gesture, forming a bonded pose that is more Hollywood red carpet than rather more formal UK royals. 

'He face-checks her to read her emotions and his suppressed smile suggests pride as well as affection. Kate looks anything but fragile with a confident smile and walk but William still seems keen to play the more traditional protective role, especially now they are on tour abroad.'

Prince William wraps protective arm around Kate in New York

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They've arrived! William and Kate stepped out of their SUV to screaming crowds at New York's Carlyle Hotel

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'It's good to be here': William gushed to door staff as he walked into the hotel hand-in-hand with Kate

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Start of a jam-packed few days: The smiling couple will fit in a number of care center visits and dinners

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Invited: Guests arrive to the lavish dinner hosted by Martin Sorrell the Prince William and Kate attended last night

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Guests: The Duke and Duchess of Cambridge arrived in New York City on Sunday, their first official visit to the U.S. since a 2011 trip to California

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Hottest ticket in town: William and Kate, who are expecting their second child in April, have scheduled a full slate of events in New York, including a visit to the National Sept. 11 Memorial and Museum and a basketball game between the Brooklyn Nets and the Cleveland Cavaliers

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Exclusive: Their visit also will include some events with other high-profile guests. Former Secretary of State Hillary Rodham Clinton and daughter Chelsea Clinton are accompanying William and Kate to a New York reception highlighting conservation efforts

Exiting their blacked-out SUV at the exclusive Carlyle Hotel on Sunday, the 32-year-old Duchess showed little sign of the illness that blighted her first weeks of pregnancy.

Now at five months, and proudly displaying a small but noticeable bump, Kate looked glowing as she smiled warmly at the waiting fans.

But despite her seeming good health, William clearly is still concerned over her wellbeing. 

As well as shadowing Kate into their hotel, where they will stay for their two day visit, William continued to remain close to Kate when they couple stepped out hours later to attend a private dinner.

Once again the prince kept his arm firmly round Kate's waist as they descended the steps of the hotel surrounded by their security.

The ‘private’ event, which is expected to raise hundreds of thousands of pounds for the couple’s charitable foundation, is being held at the cavernous Manhattan apartment of British media and marketing mogul Sir Martin Sorrell, whose personal fortune is estimated at £174million.

But this whirlwind evening looks set to set the pace for the couple's jam-packed two days in New York.

And it may be the rather frenzied nature of the visit which has William concerned for his wife.

Kate's reported desire to join him in a climb the Empire State Building today has no doubt increased the Prince's worries, but Kate seems determined not to let her second pregnancy slow her down.  

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Taking care: The Duke of Cambridge put a loving arm around his wife who is due to give birth in April

 

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Royal blue: Wills made quite the fashion statement among black suits in a deep blue number