Maybe the clone just couldnt get pregnant. Perhaps that was the point of having one of the workers get a cold, to show that his Ganger didnt also pick it up. We know Cleaves Ganger suffered headaches, but we don't know that she actually had the clot, same as Ganger Amy having the contraction pain but not the actual pregnancy?
Probably wrong but just a thought
I think that this is probably the best idea. Trying to explain away all the seperate plot strands would take way too long, but this is simple and easy to understand without seeming like a copout