What is a required criterion for the use of forceps in delivery?

The use of forceps in delivery requires that the membranes have ruptured. This is crucial because the presence of ruptured membranes helps to create a better environment for the application of forceps during the second stage of labor. When the membranes are ruptured, the clinician has clearer access to the fetal head and can better assess its position and descent in the birth canal. Additionally, the absence of amniotic fluid can increase the risk of injury to both the mother and the fetus during the application of forceps.

The other options do not align with the established criteria for forceps use. The position of the fetus is indeed important, as the forceps should be applied when the fetal head is in a favorable position, typically at or near the pelvic inlet in specific cephalic presentations. Estimating fetal weight is also important in assessing whether the fetus is within an appropriate size range for forceps delivery, as larger fetuses may present a higher risk of complications. Lastly, general anesthesia is not a requirement; in fact, forceps can often be used with regional anesthesia to allow the mother to participate in the delivery process safely.