When a calf gets in a seperate pen from its momma these are stressful times. For me I'm thinking about all the damn fence that'll need fixing if this goes bad, and the calf has it's own set of worries.
Most important thing is to go easy. Try to to bring momma to baby instead of pushing on the calf. Once baby is reunited the odds of spending the rest of the day tangled up in barbed wire are dramatically reduced.