State Police Commissioner Ikechukwu Aduba told Leadership Newspapers the suspect, identified only as Gladys, 40, lured young women to her house in Asaba, promising to help them find work.
Aduba said once the women were at the house, the suspect invited men to have unprotected sex with them, usually paying a fee.
When the women became pregnant, Gladys fed and clothed them and forbade them from leaving the house, Aduba said.
They were also made to take an oath, promising not to disclose any information to outsiders, the commissioner said.
Doctors and nurses regularly checked on the women, Leadership reported.
After babies were born, they were sold for $1,587 to $3,174, depending on their sex. The mothers were paid between $317 and $634, the newspaper said.