Pregnant?

Chris and Wendy's relationship was on the rocks. They argued all the time and just couldn't seem to see eye-to-eye on anything. A good friend of the couple knew their troubles and offered his help by sharing with them The Medallion of Zulo. "One night as each other and you'll never argue again," he said. Both thought that he was full of crap but went along with it anyway for the sake of their marriage, and both were amazed when it actually worked. The two were feeling up their new bodies and were in awe at the situation. One thing lead to another and the next thing you know, they were making love under the covers. The next day their problems seemed lifted; neither felt the need to argue anymore; however, the medallion refused to work when they tried to switch back. Their friend gulped, "It doesn't work if you're, um, pregnant." Eight months later and the couple still haven't argued a single time.