Maria said she learned her newborn daughter had been given up for adoption for which she received 20,000 naira ($65.79).
"The nurse took my child away to be washed. She never brought her back," the teenager said, gazing down at her feet.
Maria said she learned her newborn daughter had been given up for adoption for which she received 20,000 naira ($65.79) - the same price as a 50 kilogram bag of rice.
And Maria is far from alone.
A Thomson Reuters Foundation investigative team spoke to more than 10 Nigerian women duped into giving up their newborns to strangers in houses known as "baby factories" in the past two years or offered babies whose origins were unknown.
Five women did not want to be interviewed, despite the guarantee of anonymity, fearing for their own safety with criminal gangs involved in the baby trade, while two men spoke of being paid to act as "studs" to get women pregnant.
Although statistics are hard to come by, campaigners say the sale of newborns is widespread - and they fear the illegal trade is becoming more prevalent with Nigeria heading into recession this year amid ongoing political turbulence.
"The government is too overstretched by other issues to focus on baby trafficking," said Arinze Orakwue, head of public enlightenment at the National Agency for the Prohibition of Trafficking in Persons (NAPTIP).
Record numbers of baby factories were raided or closed down in the southeastern states of Abia, Anambra, Ebonyi, Enugu and Imo this year, NAPTIP said.
A total of 14 were discovered in the first nine months of 2016, up from six in 2015 and 10 in 2014, the data showed.
But despite the growing number of raids, the scam exploiting couples desperate for a baby and young, pregnant, single women continues with newborns sold for up to $5,000 in Africa's most populous nation where most people live on less than $2 a day.
Cultural barriers are also a factor in the West African nation, with teenage girls fearing they will be publicly shamed by strict fathers or partners over unwanted pregnancies if they do not give up their children, experts say.
"In southeastern Nigeria a woman is deemed a failure if she fails to conceive. But it is also taboo for a teenager to fall pregnant out of wedlock," said Orakwue.
Maria said in the home in Imo state where she gave birth pregnant teenagers were welcomed by a maternal nurse who liked to be called "mama" but went on to sell the babies they delivered.
"(After I gave birth) somebody told me that mama collected big money from people before giving them other people's babies," Maria told the Thomson Reuters Foundation in the grounds of a school compound in her village.
"I do not know where my baby is now," said Maria, using a false name for her own protection.
A lot of the trade is carried out in Nigeria but authorities suspect babies are also sold to people from Europe and the United States because many foreigners continue to seek infants there despite the controversy around Nigerian adoptions.