<p>I've printed mostly ABS in the past and encountered <a href="https://www.google.com/#q=3d+printing+layer+delamination">delamination</a> between layers many times. I've ensured the following conditions regularly:</p>

<ul>
<li>Build plate is level</li>
<li>Base of print isn't warped (using ABS slurry)</li>
<li>Prevent air draft. I've added acrylic panels to the sides of the machine and the machine is in a custom cupboard.</li>
<li>Nozzle temperature at about 225C</li>
<li>HBP temperature at about 112C (I live in NW USA, so the ambient temperature is typically fairly cool).</li>
<li>Using MakerBot filament</li>
</ul>

<p>What are some other variables to consider to help prevent delamination between layers?</p>

I know some could not fit your question but maybe someone will look for all possibilities.
Delamination can be caused by:
filament
humidity
diameter
extruder
pressure (holdfast) - soft filament can be crumpled caused by extensive retraction)
dirty jagger teeth (knurls)
thermistor/wire failure - when it reports temp under ie 170C then extruder doesn't extrude
caret floatage (extruder motor cannot pull filament so it climbs)
general
printing speed
temperature issue