It would not cause any problems because:
1) it would likely be out of her system when she conceived
2) it would only cause an issue once the placenta is developed and that doest happen until closer to 10-11 weeks.
Congratulations.
There are many differing opinions on when the risk of birth defects minimizes after stopping accutane. Her Dr. will likely monitor her very very closely and check for any malformations. When I worked at a blood bank any person that had taken accutane within the previous year was not allowed to donate blood, because of the risk of that blood being given to a pregnant woman. Of course the government is being extremely proactive in that matter, and like you, what I've read says to wait at least a month before conceiving. The baby will likely be fine, even though you didn't mean to conceive it was at a time that would have been permitted by her Dr. if you had been trying. Good luck!
Agree with Spade22.
Continual use of Accutane WILL cause birth defects. But she stopped before she even conceived and it was almost a full month before she conceived. Rest assured, your little one is fine.
I agree with Joy and Spade. I was on a medicine called Soriatane, which takes 3 YEARS to get out of your system. I got pregnant with my son TJ at just barely that 3 year mark (it used ot be 6 years...)
He didn't have any birth defects. (the down syndrome he has wasn't related to that it was something that happened pre-existing.)