Any woman who has given birth will likely say that labour was the most painful experience of their lives – so it is no surprise that Queen Elizabeth II went out of her way to absent herself from it.

The late Queen was put into a ‘twilight sleep’ when giving birth to Charles in 1948, Anne in 1950 and Andrew in 1960.

Twilight sleep, also known as dammerschlaf, was first developed in Germany by obstetricians Bernhardt Kronig and Karl Gauss in 1906.

Using a combination of the drugs scopolamine and morphine, the mother enters an amnesic state prior to giving birth and wakes up with no memory of the baby being delivered – usually by forceps.

Queen Elizabeth’s decision to use this extreme form of pain relief would have been viewed as ‘radical’ at the time.

Milli Hill, author of bestselling pregnancy guide The Positive Birth Book, exclusively told Daily Mail: ‘News travelled fast of a clinic in Germany that was offering these “pain-free” births.

‘Women began to demand twilight sleep as part of the new discourse about their autonomy, and the method spread across the USA, UK and Europe, with even Queen Elizabeth II using a version in the birth of her first three children.’

But there is a long list of sinister reasons as to why twilight sleep has been resigned to history.

As a result of being pumped full of drugs, the mother often had no recollection of giving birth – to the extent that they did not recognise their own baby.

Some mothers struggled to bond with their children as a result of the procedure, while others refused to accept they had given birth at all.

Milli explained: ‘Taken up as a way for women to gain more control in childbirth, the reality seemed very far away from this.

‘Women were placed in padded, crib-like beds, blindfolded, with cotton wool in their ears and their arms tied down or even straight-jacketed.

‘Conscious, but entirely unaware of their own actions, the women under twilight sleep would thrash around and scream at full volume, often waking with feelings of disassociation and friction burns to their arms from fighting their restraint.

‘This, along with side effects such as horrifying flashbacks, increased birth complications and even death. This caused the method to decline in popularity, but the use of scopolamine and the whole concept of “knock ’em out, drag ’em out” obstetrics pervaded for 60 or more years of the 20th century.’

While it is not clear exactly what happened to Queen Elizabeth II when she used twilight sleep to give birth to Andrew in 1960, a lady-in-waiting told royal biographer Gyles Brandreth that she suffered ‘post-natal side effects’.

And it is no coincidence that Prince Edward was born naturally four years later.