I really liked this. Very useful especially if you want to show that your birth plan preferences really are evidence-based. I'd love to see a copy of this in every maternity unit.

When and How to Push: Providing the Most Current Information About Second-Stage Labor to Women During Childbirth Education

The “old way” of assisting women during second-stage labor typically involves pushing immediately at 10 cm regardless of whether the woman has an urge to push; telling the woman to take a deep breath and hold it while someone counts to 10 during at least four to five pushing efforts per contraction as the woman lies in the supine lithotomy position (often using stirrups); and a care provider forcing the woman's legs back against her abdomen. These techniques have the potential to cause harm to the mother and baby
A better approach based on current evidence is to delay pushing until the woman feels the urge to push. With epidural anesthesia, pushing can be delayed up to 2 hours for nulliparous women and up to 1 hour for multiparous women ... The most stressful period of labor for the fetus is the active pushing phase; thus, shortening this phase minimizes fetal stress and promotes fetal well-being. When pushing is delayed until the woman's urge to push, there are fewer fetal heart rate (FHR) decelerations and less of a negative effect on fetal acid-base status and oxygenation.
When the time is right for pushing, the best approach based on current evidence is to encourage the woman to do whatever comes naturally.
wow! a published article actually says this! about time eh?

Positioning is an important component of safe and effective pushing. An upright position or lateral position works better than supine positioning
finally!

If the fetus does not respond well to pushing, the best approach is to stop pushing temporarily and let the fetus recover.
yeh, that!

I hope this is helpful for someone out there.