Doctors have used ground-breaking surgery on an unborn baby to successfully correct a birth defect while he was still inside the womb.

His mother, Maisie Savage, from London, was operated on by doctors in the US while she was 26 weeks pregnant.

Baby Theo, who is now five months old and thriving, had gastroschisis, where the belly button does not develop properly, causing the intestines to grow externally.

Doctors partially exposed his mother’s womb and then gently pushed his organs back inside his abdomen using keyhole surgery.

He was the third baby in the world to benefit from the first-of-its-kind clinical trial.

Maisie, 29, and Theo’s father, Josh French, 36, both teachers, say they are incredibly relieved by the success of the pioneering surgery.

“He’s a little miracle, isn’t he?” Maisie told BBC News.

But they both know things could have been very different.

The serious birth defect affects one in 3,000 UK babies each year. In the best-case scenarios, babies can require weeks in intensive care and nutritional feeding through a tube or IV and corrective surgery.

For the most complex cases, like Theo’s, outcomes are far more serious with up to six months in neonatal intensive care, multiple surgeries, IV nutritional feeding for up to two years, and a possible intestinal transplant.

Even with the highest level of medical care, one in 10 babies will die.