From Full Moons to Baldness

"These myths are very amusing and perhaps there was some story behind it in the past, but, no, there is no way … by telling whether it's going to be a boy or a girl," said Dr. Paula Randolph, an obstetrician-gynecologist at Columbia University Hospital.

Science does let you find out if you want to know what color to paint the nursery.

Sonograms or ultrasounds are extremely accurate after 18 to 20 weeks. But without an ultrasound, it's little more than an old wives' tale, and guessing.

So, when a woman claims, "I've got this big belly down low, definitely a boy," how does Randolph respond?

"You have a 50 percent chance of being right or wrong," Randolph said.

MYTH #4 — Is It Dangerous to Swim After Eating?

It's the danger in the water your mother warned you about: Swimming right after eating is dangerous and if you do it, you will get a cramp and maybe drown.

Dr. Tim Johnson asked a swimming class what they thought. They believed it. When he told them it was a myth, they didn't believe him.

Dr. Jane Katz has been inducted into the International Swimming Hall of Fame for her contributions as an expert on swimming. But even she can't convince this beginner's swim class at New York City's John Jay College that swimming after eating isn't dangerous.

Katz said, "Part of this myth, … is basically comfort, because after you eat you always get tired. The reason is of course your circulation is going to the intestines and sometimes if you try to exercise vigorously you get a stitch."

But even if you get a stitch, or a cramp, it's not life-threatening.

The American Red Cross agrees. We set up our own experiment with those skeptical swimmers. We had them climb out of the pool and eat a snack. We had them get back in the pool and swim vigorously.

Everybody in class felt fine. One swimmer even said he was hungry.