Remee Jo Lee says John Andrew Welden begged her not to have a baby after she became pregnant.
Lee, her attorneys and federal prosecutors say Welden forged a signature of his father, who is an obstetrician, on a prescription for Cytotec and relabeled a pill bottle as "amoxicillin." Cytotec is used to induce labor.
Welden then told Lee that his father said she had a bacterial infection and needed to take the mislabeled amoxicillin.
Lee, who was about six or seven weeks pregnant, experienced severe cramps and pain and went to the hospital. She miscarried shortly thereafter.
"Nothing is ever going to bring back what was taken from her, no matter what the result, whether this had gone to trial or not," said Todd Foster, a defense attorney in the case.
Welden claims that a Tampa-area pharmacy worker ordered the pills on his behalf and that the pills came in the mail; the pharmacy worker is an unindicted co-conspirator, the judge said. Prosecutors won't say if the unnamed pharmacy worker will be charged.
Welden's attorney says his client is remorseful. He faces up to 15 years in prison and three years of supervised release when he's sentenced Dec. 5 on charges of tampering with a consumer product and conspiracy to commit mail fraud.
Welden's father has not been accused of wrongdoing and has not been charged with any crime.
Welden is free on supervised release until the sentencing hearing.
The Associated Press contributed to this report.