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BOSTON - A worrisome national surge in multiple births linked to test-tube technology is easing, largely because doctors are implanting fewer embryos during each attempt to make a woman pregnant, a study suggests.
Doctors routinely place several embryos in the womb at once to improve the odds of producing a baby, a technique that sometimes works too well and leads to twins, triplets or other multiple births.
But technical advances and the advent of professional guidelines appear to have led to more sparing use of embryos, the study's researchers reported in today's New England Journal of Medicine.
The findings are likely to stoke the debate over whether the government should put a cap on the number of embryos that can be used for each attempt.
"It's so rapidly evolving that, to put it in the hands of legislation, is clearly to temper and limit progress," said Dr. Robert Rebar, director of the American Society for Reproductive Medicine. "The guidelines are working."
Researchers at Boston's Brigham and Women's Hospital analyzed federal data on in-vitro fertilization cases in which women had their eggs fertilized with sperm in the laboratory and then had them implanted. The technique accounts for the most laboratory-assisted fertility procedures.
The average number of embryos implanted per attempt dropped from four to three from 1995 to 2001, the last year of federal data. In the last five of those years, triplets and greater multiple pregnancies fell from 11 percent to 7 percent of all in-vitro pregnancies. The rate of twins held steady among in-vitro pregnancies.
Botswana reports first case of polio since 1991GENEVA - The southern African nation of Botswana has reported a case of polio in a 7-year-old boy - its first of the crippling disease in more than a decade, the World Health Organization said.
The U.N. health agency said the boy was infected by a virus similar to that found in Nigeria, one of the last regions where the disease has not been eradicated. WHO declared Botswana polio-free in 1991.