THE Duchess of Sussex has given birth to a baby boy.

Prince Harry is at Meghan's side as the couple welcome their son.

The baby boy is the seventh in line to the throne, and the Queen and the Duke of Edinburgh's eighth great-grandchild.

The sex was a surprise for Harry and Meghan, who chose not to find out what they are having.

Prince Harry said they were "absolutely thrilled" and thanked the public for their support during the pregnancy.

He said Meghan and the baby were doing "incredibly well", adding that they were still thinking about names for the infant, who was delivered at 05:26 BST.

Buckingham Palace said the baby weighed 7lbs 3oz, and that the duke was present for the birth.

"The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, The Duke and Duchess of Cambridge, Lady Jane Fellowes, Lady Sarah McCorquodale and Earl Spencer have been informed and are delighted with the news," added as spokesman.

"The Duchess's mother, Doria Ragland, who is overjoyed by the arrival of her first grandchild, is with Their Royal Highnesses at Frogmore Cottage.

"Her Royal Highness and her child are both doing well."

Ahead of the birth, the duke and duchess made a personal decision to keep their arrangements private, amid speculation that they had opted for a home birth at their new home, Frogmore Cottage, close to the Queen's Windsor Castle home.

They said they would only share the news of the baby's arrival once they have had a chance to celebrate privately as a family.

The newest addition to the Windsor family is a first cousin of the Duke and Duchess of Cambridge's children, Prince George, Princess Charlotte and Prince Louis, and a fourth grandchild for the Prince of Wales.

Baby Sussex's arrival comes less than a year after Harry married American former actress Meghan in a glittering ceremony in St George's Chapel, Windsor Castle.

Predicted name choices include Diana, Elizabeth, Alice, Isabella, Grace and Victoria for a girl and Arthur, Albert, Frederick, James, Charles and Philip for a boy.

A water birth or hypno-birthing could be options open to ex-Suits star Meghan during labour.

Around two in 10 women giving birth in England use water or a birthing pool for coping with pain, with one in 10 delivering in the pool.

Meghan, who is an avid yoga fan, and Harry, who meditates each day, could choose to try hypnobirthing - pain management using a mixture of visualisation, relaxation and deep breathing techniques.

A celebratory social media post is expected to announce the birth on the duke and duchess' Instagram account @SussexRoyal, coinciding with an email announcement to the press.

Royal births are usually also marked with the traditional custom of placing a framed paper proclamation on an ornate gold stand behind the iron railings of Buckingham Palace.

Meghan's pregnancy was confirmed by Kensington Palace on October 15 last year, just five months after the couple's wedding, and as they were about to start their first long-haul overseas tour.

Harry urged his wife to pace herself during the marathon 16-day trip to Australia, New Zealand, Fiji and Tonga.

The duchess pulled out of a meeting with Invictus competitors in Sydney after the Games opening ceremony overran by two hours the evening before.

Meghan has kept busy in the months that followed, announcing her first four patronages, and carrying out a steady stream of engagements, including an official visit to Morocco.

Celebrations ahead of the birth included an exclusive baby shower for the duchess in New York City, with the private jet journey and penthouse suite, reportedly funded by celebrity friends, said to have cost some £300,000.

Meghan was last seen on an official engagement on March 19 when she signed a book of condolence in London for victims of the Christchurch terror attacks.

The baby will not be an HRH, or a prince, unless the Queen steps in, because George V limited royal titles in 1917.

The boy will be able to use one of Harry's lesser titles and be known as the Earl of Dumbarton.