Vanessa George, admitted seven counts of sexual abuse and six counts of distributing and making indecent pictures of children.
She committed the crimes at Little Ted's nursery in Plymouth, where she worked.
The full details of the charges the nursery worker admitted are too graphic to report.
They describe the most depraved and degrading of sexual assaults, perpetrated on the most vulnerable of victims.
The children in George's photographs have never been identified.
By analysing electronic references stored within the images, detectives have been able to work out roughly when the pictures were taken.
With the assistance of a consultant pediatrician, they have also estimated the ages of the children involved.
By cross-referencing nursery records, they have narrowed down to 30 the number of families who would have had children of the right age, at the relevant time, in the care of George.
Co-defendants Angela Allen and Colin Blanchard also admitted a string of charges relating to assault and child pornography.
Allen, 39, (pictured above) pleaded guilty to four child sex assaults and one count of distributing an indecent image.
The unemployed single mother from Nottingham wept as she stood in the dock.
Blanchard, also 39, pleaded guilty to 17 child pornography counts and two sexual assaults on children.
It can also be revealed that Blanchard, who was married and had a young daughter, had been on the sex offenders register.
Sky News West of England correspondent Katie Stallard said there had been no suggestion of any financial motivation or coercion.
"The abuse was carried out solely for the sexual gratification of George and her two co-defendants," Stallard said.
"The three apparently first met on Facebook last year, but never actually met until they were led together into the dock at Bristol Crown Court.
"The trio traded thousands of explicit email and text messages detailing horrific fantasies of child sex abuse.
"Often they would share photos of the assaults, which were taken on their mobile phones."
One detective told Sky News they appeared to be engaged in a macabre contest to see who could come up with the most depraved idea.
Sky News has also learned George - who is married with two teenage children - even discussed with one of her accomplices the possibility of abducting a child.
Sources have said the nursery worker emailed Blanchard detailing a visit to a railway station's public toilets, where she had seen a little boy standing on his own.
She is said to have written: "It would have been the perfect opportunity to snatch him".
Blanchard reportedly replied asking whether she would drug children for him.
Police have said they will now never know whether this was pure fantasy, or the beginnings of a plan.
At Bristol Crown Court, Mr Justice John Royce urged George to reveal who her victims were.
Addressing her counsel, he said: "Your client must know, it seems to me, who she has abused and who she has not.
"If I were a parent, I would want to know whether my child was abused or not.
"Would it not be decent for her to indicate who she has abused? It is a factor that I have got to take into account."
The Crown Prosecution Service's head of complex casework, Ann Reddrop, said identifying the abused children remained a priority for police.
Angry parents at the courthouse
"The victims may be too young to understand, but their families will have to live with the effects."
The trio will be sentenced on November 13.
Source: Sky news.
Can you guys believe this? A woman, a mother... molesting young children? You would think ONLY very sick men carried out such dastardly acts. What is a woman doing molesting 18 months old babies? What is going on in our world?
