Yes, I made a comic where Optimus and Arcee have sex.
Well, yeah, that's pretty much Cybertronian fairy sex. It's kind of my own head canon theory in regards to (perhaps) the most confusing aspect of the Transformers lore, reproduction [link]
I think this would be a viable means of reproduction for Cybertronians, the partial combining of two sparks that would result in the two "partners" replicating and installing pieces of their very soul into one another. And of course it would often trigger "pregnancy" as the female would then manufacture and gestate a stable protoform within her body. Those are my thoughts anyway.