They were less likely to have had their labors induced or augmented by medications or to have had cesarean sections, forceps or vacuum extractor deliveries. (childbirthsolutions.com)
Because of the force that they produce, things like forceps and vacuum extractors often contribute to brachial plexus injuries. (peter-thompson-associates.com)
Excessive or improper use of force, and / or misuse of forceps or vacuum extractor during delivery (bwglaw.com)