An Odd Question

Dancers for Empire Of The Sun as photographed by B. MayerI was listening to a podcast the other day, and the host and his cohorts were discussing swimming with dolphins. The idea was presented that a lady pregnant with twins shouldn’t be allowed in the pool, as the animals will become confused by the dual-babies and attack the woman and her unborn.

Is this just an urban legend thats grown up around the insurance hazards of letting a pregnant person do something strenuous?

Google hasn’t provided an answer, and I’d be interested to hear if anyone has heard this before/might be able to shed some light on the situation.