NFL Star Who Wanted Another Child Faces Drug Suspension

May 20, 2014— -- One of the NFL’s leading defenders, Robert Mathis, is defending himself following a performance-enhancing drug controversy.

The six-time Pro Bowl member – and Super Bowl champion with the Colts – was suspended for four games, costing him $705,000, for testing positive for the fertility drug Clomid. Clomid is banned by the NFL because it can be used to help improve a player’s performance.

Hadley Englehard, Mathis’s agent, says Mathis was taking clomid for fertility purposes.

“Robert is not a cheater. There is not one bit of evidence that Robert used this for anything but fertility,” Englehard said.

Mathis and his wife already have twin boys and a daughter, but they wanted to give Mathis’ ailing mother – diagnosed with Stage 4 cancer – a fourth grandchild. Mathis’ wife is now pregnant.

Dr. Steven Morganstern, the Atlanta doctor who treated Mathis for infertility, told ABC News that he didn't realize Mathis was an NFL player when he prescribed Clomid. Morganstern is proud that the couple was able to conceive.

"Robert was using it, he had an increased sperm count, his wife got pregnant and he was off it," Morganstern said.

Mathis has said that he specifically asked the doctor if the medication would present a problem for NFL drug testing, but Morganstern denies that he gave Mathis any such assurance.

“That would not be something I would know,” Morganstern told ABC News.

But Morganstern believes the differing accounts are not important.

"He is an upstanding man," Morganstern said. "The whole situation was honorable."

The NFL says Mathis should have checked with the league or the player’s union before beginning the treatment.

"A cornerstone of the program is that a player is responsible for what is in his body," the NFL said in a statement. "Consistent application of the policy's procedures is critical to the integrity of the program."

ABC News Medical Contributor Dr. Jennifer Ashton said Clomid is often used by men who have low sperm count, but that it could help a player on the field.

“It has been used to enhance athletic performance because it can raise testosterone levels,” she said.

ABC News Chief Legal Affairs Anchor Dan Abrams said the NFL had no choice in the matter.

“They had to draw a firm line – if you take a banned substance without clearing it with us, and you get caught, then you’re going to get punished even if you took it for some other reason than enhancing your athletic performance,” Abrams said.

After the NFL announced its decision, Mathis took responsibility in a statement online.

“I am deeply saddened that this situation will prevent me from contributing to my team for four games, and I regret that I didn't cross check what my doctor told me before I took the medication,” Mathis wrote. “I hope that my fans will understand the unique circumstances involved here and continue to know that I am a man of integrity who would never intentionally circumvent the performance enhancing substance policy agreed to by the NFL and my union.”

Colts head coach Chuck Pagano is standing behind his player.

“He’s a horseshoe guy. He’s a pillar guy. We’ve got his back,” Pagano said.