LA CROSSE, WISCONSIN 

You can excuse Dr. Kenneth Merkitch if he's seeing double these days. He's been an obstetrician-gynecologist at Gundersen Lutheran Medical Center for 19 years, but he said he's never experienced a 24-hour on-call period like the one he put in on Friday and Saturday, when he delivered four sets of twins.

"I don't think I ever delivered two sets of twins on a call day," Merkitch said.

"It was hard to believe that everything was coming in twos, but after a while you're up all night, you might as well keep delivering babies," he said. "It's something I don't think I'll see again."

Merkitch delivered one other baby during his shift; he also couldn't recall ever delivering nine babies during a similar shift.