Sound asleep and serene, Siamese twins Faith and Hope are surviving despite the odds

Their arms are wrapped around each other as they sleep peacefully. But this picture of serenity is one Faith and Hope's parents might never have seen.

For when Laura Williams was told she was pregnant with Siamese twins, she and her husband Aled, 28, were advised to abort them. Although the survival rate for conjoined babies is very low, the couple, from Shrewsbury, refused on moral grounds.

On Wednesday their girls were delivered by Caesarean section, with a combined weight of 10lb 8oz. Mrs Williams, 18, the youngest woman to give birth to conjoined twins, told The Mail on Sunday: 'They wheeled me in to see them.

'They had tucked Hope's arm underneath and it was Faith's arm that I could see. I took her hand and she was grasping my hand.

'They were both blowing bubbles. They were so beautiful. After everything everyone said, I'm so glad to have proved them wrong.'

Conjoined twins are caused when the single egg from which identical twins develop fails to divide fully.

The survival rate is between 5 per cent and 25 per cent. Faith and Hope, joined from the breastbone to the navel, were delivered at University College Hospital, London.

The delivery involved a medical team of 30, with two sets of implements. Obstetric consultant Pat O'Brien said: 'The birth went as well as we could possibly have hoped for.'

They were then taken to Great Ormond Street Hospital.

Although the girls are stable, they have abnormal hearts, share important blood vessels and are joined at the liver and intestine, said paediatric surgeon Agostino Pierro. 'The current concern is that the two hearts and joined circulation raise a risk that the children might suddenly deteriorate and need emergency separation surgery.'

The babies would normally be separated when older and stronger but doctors will decide whether to operate this week.