The birth of a royal baby is always a joyous occasion, but both of Prince Edward and Sophie's children endured health scares shortly after they arrived in this world. Now the Duke and Duchess of Edinburgh, Edward and Sophie are the proud parents of Lady Louise Windsor, 22, and James Mountbatten-Windsor, who turns 18 today. By the time James was born on December 17, 2007, Sophie had endured an ectopic pregnancy as well a rather traumatic birth when she underwent an emergency C-section before Louise was whisked away to receive specialist care.

Her premature birth left the Duchess '15 minutes from death' while young Louise developed esotropia - a rare condition which means that both eyes do not look in the same direction. Considering Sophie's experience with Louise, she was naturally 'very concerned' when her newborn son James developed a mystery illness and was 'rushed' to a Londonhospital five weeks after his birth. Royal author Sean Smith described how Sophie and Edward 'put on a brave face' when James was admitted to the Great Ormond Street Hospital, where he underwent 24 hours of tests.

Much to their relief, it was later announced that James had suffered a 'nasty allergic reaction' due to lactose intolerance, Mr Smith said in his book Sophie: The Biography. 'Fortunately, because he had been taken to hospital so quickly, there were no lasting effects,' he continued. Sophie and Edward were married in June 1999 at St George's Chapel in Windsor. Considering the royal scandals that preceded their wedding, Sophie and Edward were forced to wait for the right time to walk up the aisle - meaning the bride was 34 by the time she said 'I do'. Sophie was keen to start a family as soon as possible and, much to her delight, fell pregnant in the winter of 2001.

However, six weeks later, Sophie suffered an ectopic pregnancy - meaning the fertilised egg implants itself outside the womb, usually in a fallopian tube - and had to undergo immediate surgery. Lady Louise's premature birth was also difficult for Sophie, then the Countess of Wessex, who suffered an acute placental abruption and was reportedly just 15 minutes away from dying in the emergency room at Frimley Park Hospital, Surrey. It took a massive blood transfusion - around nine pints - before she regained any kind of stability. Lady Louise, who weighed just 4lb 9oz, developed a sight disorder, but Sophie has since confirmed 'her eyesight is perfect' after her daughter underwent surgery to correct the squint.

Four years later, Sophie - who was keen to have another child with Edward - decided to take a break from IVF treatment before she fell pregnant again without any kind of medical intervention. In July 2007, Buckingham Palace announced that Sophie was 'expecting a baby in December', adding: 'The Queen and The Duke of Edinburgh and members of both families are delighted with the news'. James Alexander Philip Theo Windsor-Mountbatten weighed a healthy 6lb 2oz when he was born on December 17, 2007, via a planned C-section at the same hospital as his sister in Surrey. 'As another gesture of thanks, Sophie decided to have the baby - again by caesarean section - at Frimley Park Hospital,' Mr Smith wrote in the Duchess's biography.

While James's birth went smoothly, his parents were 'very concerned' as they rushed him to the Great Ormond Street Hospital five weeks later. A source told People at the time: 'Sophie arrived just after 3 p.m. You could tell by the looks on their faces that they were very concerned. They rushed upstairs straightaway and went immediately into a consultant’s room.' Fortunately, the royal baby had only had an allergic reaction as a Palace spokesperson confirmed his condition was 'not life-threatening and not serious'. Ever the professional, Edward even continued his public engagements as planned during James's hospital stint, including opening a new high school in Bromsgrove, Worcestershire.

Paul Copeland, head of South Bromsgrove High School, later recalled his surprise at Edward's appearance, given his son's illness, stating: 'We thought he might not come but when we saw him arrive, we thought it was fantastic.' Inspired by the incredible work of the medical team at Great Ormond Street, Sophie has continued to support the hospital through several charitable engagements and fundraising initiatives over the years. When he was born, James was eighth in line to the throne. His sister Lady Louise had been relegated to ninth place due to the now-defunct male-preference primogeniture tradition. Scrapped in 2013, the rule previously dictated that the eldest son would be given priority in the line of succession.

Three months after the health scare, James was christened in a ceremony held at Windsor Castle's Private Chapel. Historically, he was the first royal to be dressed in the new replica of the traditional lace and satin royal christening gown, commissioned by Queen Victoria in 1841 for her firstborn daughter, Victoria Adelaide Mary Louisa. Known as the Honiton christening gown, the replica was made by the Queen's senior dresser, Angela Kelly, and has since been worn by every new royal baby for the event. The late Queen Elizabeth was pictured smiling proudly at the christening of her youngest grandchild, alongside her husband Prince Philip and Sophie's fatherChristopher Bournes Rhys-Jones.

James was also styled Viscount Severn, one of Edward's secondary titles, which can only be passed down the male line, while Louise continued as Lady. Yet their differing titles had no impact on the close bond already developing between the two royal siblings - with one observer telling Mr Smith how then four-year-old Louise 'kisses him and cuddles him and is a real little mother to him'. 'It's lovely,' they added. Both Louise and James grew up without HRH titles after Sophie and Edward decided to give them as normal an upbringing as possible. While Lady Louise, who is currently studying English at St Andrew's University, has started stepping out more often, James has kept a low profile. He is currently completing his A-Level studies at the prestigious Radley College school in Oxfordshire.

As James takes his first step into adulthood, speculation about his future role in the monarchy will likely increase - as royal watchers will be keen to see whether he follows in his sister's footsteps and heads to the prestigious St Andrew's university. Writing in his Palace Confidential newsletter last year, the Daily Mail's Diary Editor Richard Eden expressed that a growing contribution from Edward and Sophie's children could be of great value to the Royal Family. He wrote: 'When Prince William becomes King, I hope that he will follow the example of his grandmother, Queen Elizabeth, and ask his cousins, including Lady Louise and James, to share royal duties with him. 'Hopefully, William will realise that a "slimmed-down" monarchy wouldn’t safeguard the institution, as some claim, but would lead to its irrelevance and eventual death. 'What better way to build on its strengths than with an injection of energy from young people who have had values of public service and duty instilled in them from birth?'