What are some things that could go wrong in labor?

Baby too big: The most common things that could go 'wrong' are that the baby is too big for your pelvis. If this happens you would need a c-section.

Too many to list: Remember that baby (& the placenta)has been in a somewhat stress free environment & the onset of labor changes the rules quickly. The stress of labor can reveal a borderline or inadequate placenta. Multiple cord wraps around the neck, true knots, infection, trauma, failure of labor to progress. These & many other issue can require aggressive surgical managemend.