Two men and a woman from Bulgaria are due to appear before a judge in the Greek capital, Athens, charged with trafficking in new-born babies.
By Richard Galpin
BBC Athens correspondent
The three are accused of holding a teenage Bulgarian girl, who is eight months pregnant, in a flat in Greece in order to sell her baby.
The girls' mother is also wanted in connection with the case.
Trafficking in new-born babies is not uncommon in Greece. There have been a number of cases over the past decade.
The heavily pregnant girl, who is believed to be 16 years old, was brought from Bulgaria into Greece at the beginning of this month.
The three suspects then kept her in a flat in central Athens waiting for her to give birth.
But according to the Greek authorities she managed to escape on Saturday and told her story to the local police.
The Bulgarian nationals who had been holding her were quickly arrested.
A public prosecutor has already charged them with human trafficking and illegal detention.
The police say the girl's mother, who is currently in Bulgaria, had allegedly agreed to the plan to sell the baby for adoption in Greece.
There have been a number of such trafficking cases over the past decade in Greece, often involving women from Albania and Bulgaria.
There are very few babies available for adoption in Greece as the birth rate in the country is so low.