Coworker has a stutter- what should I do/not do?

Coworker has a stutter- what should I do/not do? Someone I work with (like maybe 1x/week) has a stutter. We work in healthcare, and we have to communicate. She has to give me information. It can't be via email or phone or text. She has to verbally give me the information. I've never really been around someone who stutters and I don't know what to do/not do. Like is it okay that if I know what she is trying to say, is it okay to finish the sentence for her? Or should I wait for her to get it out? I don't know what the etiquette is and I don't want to do things that make her life worse. KWIM? I don't want to be an asshole. TIA