Kate Middleton
Catherine, the Duchess of Cambridge.Reuters

Kate Middleton and husband Prince William, who are expecting their second child, were photographed leaving a medical clinic in London last week, the first time she was seen out in public since announcing her pregnancy six weeks back.

Middleton has been away from public engagements for a while, as she has been suffering from a severe case of morning sickness. She was last seen in an official capacity during the poppy installation at the London Tower on 5 August.

Since then she has been resting to regain her health, and in the photos obtained by New York Daily News, Middleton looks healthy and she is seen smiling. The Duchess also appears to have put on some weight.

Reportedly, the royal couple's visit to the clinic was to do a pregnancy scan and ultrasound, and according to the publication, Prince William was seen clutching an envelope said to be containing images of their second child's first trimester scan.

While there is no official confirmation on the gender of the second royal baby, who is due sometime in March or April, speculation has been rife that it could be a girl. Reportedly, both William and Middleton have wanted Prince George to have a baby sister.

"Kate has always wanted a daughter, and she's talked about it so much that William did too," an insider told OK! Magazine. "Kate's upbringing with Pippa was idyllic and she always wanted to have girls of her own to carry on the legacy of strong, happy women. Plus, she thinks George having sisters will be tremendously good for his character."

The source continued: "William has always joked that he'd be a terrible father to a daughter because she'd have him wrapped round her little finger. But growing up with so many boys around him—Prince Charles and two uncles, plus Prince Harry, of course—he thinks it's time for more girls in the family line.''

The royal couple is also said to have decided a name for their second child, with reports suggesting that the girl baby will be named Diana after William's mother. Other popular baby names include Victoria, Alexandra, Elizabeth and Mary.