The extended royal family has grown by one again. Pippa Middleton, sister of Duchess Catherine and sister-in-law of Prince William, welcomed a baby boy.

It is the first child for Pippa Middleton and her husband James Matthews, Express reported.

The baby weighs 8 pounds, 9 ounces and was born Monday afternoon, CNN and Press Association reported.

Pippa gave birth in the private Lindo Wing of St. Mary's Hospital in Paddington, west London, CNN reported. It is the same hospital where her older sister Kate gave birth to her children.

>> Read more trending news

Kensington Palace issued a statement on the birth of the baby, saying "The Duke and Duchess of Cambridge are thrilled for Pippa and James," Express reported.

It is not expected that Kate will visit Pippa at the hospital, but will meet her sister and her new nephew in private, much like what Pippa did.

The Matthews were married last May at St. Mark’s Church in Englefield, England.

The couple just last week attended the wedding of Princess Eugenie in Windsor, CNN reported.

The baby’s arrival came shortly after the news that Prince Harry and Meghan Markle were expecting a baby next spring.

Pippa Middleton Marries Hedge Fund Manager James Matthews