Richie said she took Vicodin for menstrual cramps, but she never thought it would affect her driving.
When asked whether she is still taking Vicodin, Richie said, "No. I don't take anything now."
Richie changed her plea to guilty Friday and was sentenced to four days in jail. She has until Sept. 28 to serve the term.
She told Sawyer she pleaded guilty to the charges in order to take responsibility for her actions.
"I have a responsibility, and it's something that I did wrong, and if I could personally apologize to every single person that has lost a loved one from drunk driving I would," Richie said about her recent guilty plea. "And unfortunately, I can't, but this is my way of paying my dues and taking responsibility and being an adult."
Richie said that the reality of what she did sank in one night when she and Madden were watching a television show broadcasting images of children who had been killed in drunken-driving accidents.
She thought of her own baby then, saying that she and Madden had their first "parent moment" together.
"I owe the baby my life. I owe this baby everything and I have a responsibility now," Richie said. "Besides being responsible for myself, I'm now responsible for someone else. And I have to set the right examples. I have to really be someone that I would want my child to look up to."
Madden said he's certain he made the right decision by sticking with Richie.
"I bet on her, yeah, exactly, and that's what I did and I won," Madden said.