My 15 lbs. male dog mated with my 6 lbs. female. Will there be complications in pregnancy or birth?

I doubt it :) I have a 16 week old rottweiler terrier hound mix puppy, & his dad was a 135 lb pure bred German rottweiler, while his mom was a terrier hound mix that is only 25 lbs o.O so your puppies & momma dog should be just fine :)