My wife had a spigelian hernia from college sports repaired via a mesh patch about 3 years ago. how should we approach her first pregnancy?

Not a problem: The mesh will likely not complicate her pregnancy. Of course this depends on the location and if she may require a c section.

Nothing special: Should cause a problem at all. Let you OB know if she needs a c-section. Consider getting he old operative report. I have seen many women with prior mesh ventral hernia repairs do very well with pregnancy, and both vaginal delivery and c-section. Best of luck!