She sighed. "It's well known—even by you—that the free-fall condition has a weird effect on certain people. The human body is in an unprecedented situation in free fall. Biologically it has experienced the condition for very short periods—falling out of trees, or on delayed parachute jumps. But it isn't constituted to take hour after hour of fall."
"What about floating in a pool for hours?" asked Marcia sullenly.
"That's quite a different situation. 'Down' exists when you're swimming. Free-fall means that everything around you is 'up.' The body's reactions to free-fall go much deeper than space-nausea and a mild feeling of panic. When there's a glandular imbalance of certain kinds, the results can be drastic. Apparently some instinctual part of the mind reacts as if there were a violent emergency, when no emergency is recognized by the reasoning part of the mind. There are sudden floods of adrenalin; the 17-kesteroids begin spastic secretions; the—well, it varies in individuals. But it's pretty well established that the results can be fatal. It kills men with prostate trouble—sometimes. It kills women in menopause—often. It kills women in the early stages of pregnancy—always."
"But how?" asked Marcia, interested in spite of her resentment.
"Convulsions. A battle royal between a glandular-level panic and a violent and useless effort of the will to control the situation. Muscles tear, working against one another. Lungs rupture and air is forced into the blood-stream, causing embolism and death. Not everything is known about it, but I would guess that pregnant women are especially susceptible because their protective reflexes, through and through, are much more easily stimulated."
"And the only thing that can be done about it is to supply gravity?"
"Or centrifugal force (or centripetal, depending on where you're standing, but why be technical?)—or, better yet, keep those people off the ships."
"So now Jack will spin the ship until I'm pressed against the walls with the same force as gravity, and then everything will be all right."
"You make it sound so simple."
"There's no need to be sarcastic!" Marcia blurted. "Jack can do it. You think he can, don't you? Don't you?"