The Marseille family landed in hot water with French authorities after they reportedly paid a team of people-smugglers for the baby.
The parents, Carmen and Mike, bought the child in 2013 after trying unsuccessfully for ten years to have children. They claimed that the situation was nothing more than a win-win for everyone involved.
"We didn't think we had done anything wrong," they told French channel BFM TV. "We saved a baby from poverty."
"As far as we know, this baby may have died if it wasn't for us."
They now face fines of up to €30,000 and up to two years in prison.
The child, who is now 22 months old and lives in foster care, is understood to have been the seventh child born to a Romanian
family, whose mother could not afford to raise another.
The story of the couple emerged as ten people went on trial on Tuesday suspected of being part of a human trafficking ring - with a 32-year-old Romanian man and his three sisters said to be the ringleaders.
The people smuggling ring itself is understood to have been implicated in several similar cases.
In fact, a whole network is believed to be in operation in the southern city, with smugglers quick to bring pregnant Romanian women across the border to give birth in France, only to give up the baby for "adoption" afterwards - usually for €10,000.
Midwives tipped off police after they noticed suspicious behaviour in the maternity ward after a young mother was in tears after giving birth, while another young couple hardly left her bedside.
The court case is expected to finish on Wednesday, with the ringleaders facing up to ten years each behind bars.