Just a little help.
Variables can happen anywhere. They are a sign of cord compression. They are typically "V" shaped. They can happen before, during or after a contraction. The umbilical cord can be compressed as a hose, from pressure, kinking, tightening, knots.
To treat... fluids and repositioning mom to hopefully take the pressure off the cord, reposition it or the babe. Some are not curable i.e. knots but may be helped a bit by repositioning mom/babe and fluids.
They are a "type" of deceleration.
Lates are a sign of placental insufficiency due to anything along the line from mom's heart to baby's heart. Could be disease related on either side or the placenta itself. Late term placentas tend to calcify and may be the culprit as well. They are typically "U" shaped. If you start out with really typical lates and they over time loose their depth or the variablity you need to be MORE concerned as the babe is loosing it's reserve. Don't watch repetative lates without calling the doctor to consult. 1 late in and of itself is not necessarily ominous however, repetative are to be concerned with. Again, reposition, fluids, and O2 are called for and find out the WHYs. You may be able to treat some of the whys. Sometimes not and delivery is your option.
Early decelerations is head compression. Your baby's head is being squeezed. Check her cervix... she may be complete