Lesley Brown, 64, the mother of the world's first "test-tube baby," died on June 6 in Bristol, England.

Her death was caused by complications of a gallbladder infection, said Michael Macnamee, executive director of the Bourn Hall Clinic in Cambridge, where the in-vitro fertilization technique that produced her daughter Louise was developed.

Louise Brown's birth on July 25, 1978, was an instant global sensation and a turning point in the treatment of infertility. Since then, more than 4 million babies worldwide have been born through in-vitro fertilization, in which sperm and eggs are mixed outside the body, and the resulting embryos are transferred into the womb.

In-vitro fertilization is an established treatment now, but in the 1970s, it had failed in about 60 couples.

Then Lesley Brown and her husband, John, came along. They had been trying for nine years to conceive, but she became pregnant on the first try.

Four years later they had another daughter, Natalie, also conceived by in vitro, also on the first try.

NEW YORK TIMES