Kate Middleton Baby Bump, Due Date [PHOTOS]: Pregnant Duchess Fears Early Labor After Kim Kardashian's Surprise Delivery, Backs Out of Royal Wedding

Two of Kate and William's closest friends,Thomas van Straubenzee and Lady Melissa Percy, were married today, but the pregnant Duchess of Cambridge was not in attendance as she is only weeks away from giving birth to her first child, the future heir to the throne. Another closely watched celebrity pregnancy ended with a 5-week-early delivery last week when Kim Kardashian gave birth to Kanye West's daughter. Do you think this is why Kate decided to skip the wedding today?

Prince William, who just celebrated his 31^st birthday, and his brother Prince Harry served as ushers to Thomas van Straubenzee as he wed Lady Melissa Percy at St Michael's Church in Northumbria this afternoon. Lady Melissa is youngest daughter of the Duke of Northumberland. Also in attendance were Prince Harry's girlfriend Cressida Bonas, Pippa Middleton, and Princesses Beatrice and Eugenie.

When Kate backed out of going to the wedding, a royal source explained, "The birth may be a few weeks off, but there is still a very slim risk she could go into labor. Kate is gutted - as are Tom and Melissa - but she decided not to take any chances."

Kate is not the only one worried about her due date: her husband is stressing out about his grandfather's health. The husband of Queen Elizabeth II recently left the hospital to recuperate at home from stomach surgery. This surgery is the latest in a long line of health issues.

Prince William has always been close with his grandfather, so he and Kate definitely want him involved in their child's life.

"Wills and Kate are deeply concerned for Philip," a source revealed. "They know he'll 
be one of the people who'll provide support and love 
for their child."

"People forget how supportive Philip was to Wills when he was suffering the loss of [his mother] Princess Diana and how he was the one who advised him to wait and make sure he married a girl of his own choosing," the source added. "Philip's always been proud of William and was delighted with his choice of bride. He's excited about the pregnancy."

Here's hoping Prince Philip has a full recovery so that he can enjoy some time with his great-grandchild.