A Monitrice provides all the care and labor support of a doula AND additionally provides:
Limited clinical assessments
Monitor mother’s vital signs during labor
Monitor babies heartbeat during labor
Check cervical dilation
If your goal is to labor at home as long as possible, you may prefer the reassurance of the assessments a monitrice performs.
The best candidates for hiring a monitrice rather are first-time mothers and women planning VBACs (vaginal birth after cesarean). It can be very tempting to leave earlier for the hospital in both of these situations, and once you get to the hospital too early, you may very well find yourself confronted with interventions you were hoping to avoid.
Statistical Benefits of Having a Doula or Monitrice
50% reduction in the cesarean rate
25% shorter labor
60% reduction in epidural requests
40% reduction in oxytocin use
30% reduction in analgesia use
40% reduction in forceps delivery
http://www.childbirth.org/articles/stats.html (Admittedly, the primary source here is old, but there are more current studies to be found in a basic Google Scholar search.)