Fenestration in the forceps blade mainly helps in which of the following function?

Forceps consist basically of two crossing branches. Each branch has four components: blade, shank, lock and handle.Each blade has two curves: the outward cephalic curve conforms to the roundfetal head, and the upward pelvic curve corresponds more or less to the axis ofthe bih canal.Some varieties have an opening within or a depressionalong the blade surface and are termed fenestrated or pseudofenestrated,respectively. These blade modifications permit a firmer grasp of the fetalhead, but at the expense of increased blade thickness, which may increasevaginal trauma.In general, fenestrated blades are used to deliver a fetus with a molded headwhich is common in nulliparous women.The forceps with thin smooth blades are used for a fetus with arounded head, which is more characteristic in multiparas.(Ref: William's Obstetrics; 25th edition)