A Florida man who has pleaded guilty to tricking his girlfriend into taking an abortion pill, which allegedly led to a miscarriage, is awaiting sentencing as his lawyers are trying to prove that a single dosage could not have been enough to cause the death of the unborn baby.

Defense expert Rebecca Allen, arguing on behalf of 29-year-old John Welden, who faces 13 years and eight months in prison if found responsible for the unborn baby's death, has said in an affidavit that it is "impossible that one 200-microgram tablet of Misoprostol caused serious bodily harm to (Lee). At most, one 200-microgram tablet may cause slight nausea, diarrhea, transient fever/chills, or minor abdominal discomfort."

"It would be impossible with regard to causation, for any medical professional to definitely conclude that one 200-microgram tablet was the actual cause of any harm whatsoever," Allen added, according to The Tampa Tribune.

Two prosecution experts from the University of South Florida testified on Wednesday, however, that it is highly likely the Cytotec, another name for Misoprostol, caused the miscarriage.

"(The drug) did exactly what it was intended to do, and that resulted in the demise of the embryo," argued OB-GYN expert Catherine Lynch.

In May 2013, Welden was charged with murder under the "Protection of Unborn Children Act" after he tricked his girlfriend at the time, Remee Jo Lee, into taking an abortion pill after finding out that she was pregnant.

According to a report by Assistant U.S. Attorney W. Stephen Muldrow, the Florida man forged the signature of his father, a practicing OB/GYN doctor, on a prescription to obtain the abortion drug Misoprostol, after Lee told him she planned to raise the child on her own.

Welden is said to have acquired the drug from a local pharmacy, switched the label on it with the common antibiotic Amoxicillin, and had given it to Lee, telling her that his father wanted her to take the pill for a bacterial infection.

After taking the pill the next day, Lee began experiencing abdominal pain and bleeding.  By the time she got to the hospital, however, she found out that she had lost her six-week-old unborn baby.

"Quite frankly, your honor, this case shocks the conscience," Muldrow said about Welden's confession.

"This was a senseless crime. He had no reason to kill the baby – his baby. She had a name for the baby … This case is solid. The crime is heinous."

The 29-year-old man escaped a possible life sentence after he pleaded guilty in a Florida court in September. It was later revealed that Welden tricked Lee into taking the abortion drug because he did not want his other girlfriend finding out about the relationship.

"I woulda had my kid and I woulda been fine with that... woulda told my parents it was someone else's. I wouldn't have bothered you for money. I wouldn't have bothered you at all," Lee told Welden in a transcript of a conversation between them recorded by police.

Pharmacology expert Daniel Buffington has argued that Misoprostol can be safely used to treat gastric ulcers, but can cause miscarriages in early pregnancy. He added that no exposure to it is safe for women wishing to avoid abortion, and that the drug "contributed to or directly resulted in the termination of (Lee's) pregnancy."

U.S. District Judge Richard A. Lazzara has said it must be proven that Lee suffered harm before he can impose Welden's sentence.