The study included all women taken to C-section who received subarachnoidal fentanyl in the anesthetic mix, operated between January 1st, 2007 and December 31st, 2008; they were categorized as eligible or as candidates to participate in the study, and were included in a database.
Se incluyó a todas las mujeres llevadas a cesárea que recibieron fentanilo subaracnoideo en la mezcla anestésica y que fueron intervenidas entre el 1 de enero de 2007 y el 31 de diciembre de 2008; se las catalogó como elegibles o candidatas a participar y se las incluyó en una base de datos.