Rules meant to keep mad cow disease out of the United States are preventing American women from getting pregnant.Okay, that needs some explanation, which the Washington Post supplies. What happened is that the U.S. banned the importation of various, er, items from Europe, where the untreatable illness Creutzfeldt-Jakob disease (i.e., mad cow) was found. This included frozen sperm. It seems that a number of American women have used Danish sperm to conceive — the Danes are tall, blond and went to good schools. ("The demand was huge," said one Danish sperm bank teller.) "Oluf," "Finn" and "Dane" were popularBut when the mad cow restrictions were put into place, imported sperm was on the list of banned substances. Many experts don't see much harm coming from the icy substance. Meanwhile, American women are jumping on planes to Denmark to take possession directly.