Police said the mother of the infant, born at a hospital in Kulamangalam in the district, decided to sell the baby for money and sought the help of the doctor couple Rajasekharan and Shanthi, who inturn struck a deal with Chitra Bai, running a home for women in the city.
Chitra bought the baby for Rs 5 lakh, and planned to sell it for a profit, they said.
Following a tip-off regarding sale of the baby, police and child helpline members under the pretext of buying the infant contacted Chitra.
Chitra was also arrested, police said.
A case has been registered under Anti-Human Trafficking and Child Protection Act against the six, police said.