This is a time of major multitasking. You have to keep an eye on the monitor strip, the doctor, the patient as a whole, the perinium in particular. While you're tying the provider's gown, watch Mom's bottom, I've seen babies precip while the MD has his/her back turned putting on gloves. Have your meds ready: local (even is she has an epidural, she may need some for any repair), oxytocin, etc. Is she at higher than usual risk for PPH--large baby, long labor, infection, grand multip--if so you might want Methergine, Hemabate, or Cytotec in the room. You've prepared the infant warmer, you checked it at the beginning of your shift or when you admitted the patient, but check it again for O2, suction, the laryngoscope (is the bulb screwed in tightly, are the batteries fresh, do you have 2 sizes of blades), tubes, airways, and so on. Watch the delivery closely, glance at the clock when the head is delivered in case the shoulders get stuck, you want a good idea of how long. Did he cut an epis? Get the suture ready.
Tell your preceptor that you're feeling shakey on deliveries and perhaps you can spend a day just doing deliveries (depends on the size of your unit) Reherse different scenerios with your preceptor. What will you do if this happens, then what next?
Relax. This is a scary time. You're starting to develop some comfort with your skills, but you're still scared you'll forget something important. Remember you're never alone (or shouldn't be). There are more experienced nurses around, ask for help. Share your fears. You'll do well.