Pregnancy NANDA

This is being a little nitpicky, but I'll throw it out there just FYI: unless you're seeing decels with that minimal variability or a total absence of accels and a lack of returning variability, baby isn't likely experiencing impaired gas exchange just from the fentanyl administration.

Mom's BP isn't low and her pulse isn't unusually high, so those factors wouldn't suggest any perfusion issues on mom's end. Minimal variability on its own doesn't necessarily suggest a perfusion/acid-base concern with baby, and some kiddos just have high baselines, so if baby was riding in the 160's before the fentanyl with good variability, I wouldn't be overly concerned. The etiology behind minimal variability after fentanyl administration is that fentanyl crosses the placenta and affects baby just like it affects mom: with drowsiness and a correlating change in FHR.

Yes, fentanyl can adversely affect FHR, so it certainly warrants watching as you would with any narcotic administration in a pregnant mom, but without more description, I can't tell if you've got a category II vs category III strip on baby. Based on the info at hand, however, I think it's a little early to say baby's experiencing an impairment in gas exchange. You're in that pesky "wait and see" phase of the assessment.