OK, this is completely 'out there', but in a Dutch soap there's now a teenage character who is pregnant, and her stepmum is faking her pregnancy. The plan is that the teenager will go abroad once she starts to show, so nobody will know that the girl was actually pregnant. The baby will then be brought into the family as her baby sister or brother, and nobody will know the difference..
Maybe... just maybe.... Beyonce is not really pregnant, but has someone else who will carry and have the baby for her. This way the baby will still be 'hers' without the physical problems that go with being pregnant. She will not have to miss a day's work, no weight worries, and heaven forbid, no complications at birth...
I know some stars have had surrogates, but they were usually a lot older than Beyonce. Maybe she feels she's too young to get away with it and thinks she'll get moaned at for not having her own child, esp. when she is healthy and could carry her own baby?
If not: she's got one strange baby bump!