Louise Brown was born 25 July 1978 in England.

From all reports, the birth itself was uneventful. But it marked a turning point in treating infertility: Brown was the first child conceived through in vitro fertilization (IVF). The technique—in which an egg is fertilized outside the body then implanted in the woman’s uterus—was pioneered by British researchers Patrick Steptoe and Robert Edwards after a decade of failed attempts and moral quagmires. At the time, the concept of assisted reproduction was denounced on religious, political and scientific fronts. The Vatican issued a formal statement against it. The U.K.’s Medical Research Center refused public funding of the project. And in the United States, lauded scientist James Watson warned a congressional committee that “all hell will break loose” if IVF was successful.

The British team turned to private sponsors to keep their efforts going. When Lesley Brown and her husband volunteered for in vitro in 1977, the project finally moved from theory to execution.
After Louise Brown’s birth, demand for IVF skyrocketed, defying controversies and opponents. Today it’s estimated that more than 8 million people can trace their origins back to the technology. By 2100, IVF babies or their descendants could account for as much as 3.5 percent of the global population, according to a study from Reproductive BioMedicine Online.

“So many things have changed in the decades that have gone by,” Louise Brown wrote in a U.K. Independent article marking her 40th birthday and the anniversary of IVF. “But the desire for couples to have babies has not.”