No, they cannot. Clones are sterile. If they somehow were able to create a fetus in a womb....and made it to labor....the pain would cause them to *poof* and the jutsu caster would all of a sudden feel very very bad. Like a train was trying to exit thru their body. Thats how it was described to me at least....or like trying to push a watermelon out of a hole the size of a lemon....ouch! Oh yea...& there would be a baby in midair where the clone was at.... actually Im starting to see the plus side to this! You have the clone carry your baby, then poof it away and have your baby as soon as labor starts! Bada-bing bada boom! All the baby, no annoying pregnancy or labor! LOL Now why didn't Madara use this method with Hashirama to get a clone baby with both Uchiha and Senju DNA hmm