Every… Single…. Akiyama, H. This means that the substituents attached to the both the diene and the dienophile retain their stereochemistry throughout the reaction.
Organic Chemistry: Structure and Function. Corey, J. The complexed dienophile becomes more electrophilic and more reactive toward the diene, increasing the reaction rate and often improving the regio- and stereoselectivity as well.
This means that whenever a bridged ring is formed, the substituents bonded to the dienophile are either trans or cis to the bridge.