After an emotional debate, German lawmakers voted Thursday to allow a procedure that looks for genetic disorders in embryos before they are implanted in the womb.
Lawmakers voted 326-260 to permit the procedure known as pre-implantation genetic diagnosis under strict conditions after a debate that cut across party lines. Eight abstained.
The procedure is sometimes used after in-vitro fertilization, when parents whose families have a history of genetic disorders want to avoid having a child with a lethal or severely debilitating birth defect.
Elsewhere in Europe and in the U.S., the test is often used in infertile couples who have failed in previous attempts to have children while using IVF in hopes that the test will boost their chances of implanting the best embryo.
The procedure's legality had been a gray area in Germany. Parliament took up the issue after a federal court last year ruled that a doctor who had performed the procedure hadn't committed any offense.
Under the law approved Thursday, an ethics commission will have to decide on a case-by-case basis whether couples can use the procedure. An expert would have to certify that a couple's child faced a high risk of a serious genetic disorder or that a miscarriage or stillbirth was likely.
A large minority of lawmakers favored a total ban, with some saying that even limited permission for genetic selection set a bad precedent.
"This is about variety: Do we want to allow it in our society?" asked Katrin Goering-Eckardt of the opposition Greens, one of those advocating a ban.
But lawmakers who backed allowing the practice said it would be an option only in a few cases, and argued that parents who worry about possible genetic defects should be trusted to decide.
"I am firmly convinced that we should not choose to close our eyes to how we can use modern medicine appropriately to support and help these long-suffering families," said Labor Minister Ursula von der Leyen.
Opposition lawmaker Soeren Bartol said he wanted to give couples at risk of passing on genetic disorders the option of deciding to have a child.
"I would also like these parents to be spared, as far as possible, the terrible experience of a miscarriage or a still birth," he added.
Debates on procedures that involve genetic selection tend to be tinged in Germany by memories of the country's Nazi past including experiments on humans, but lawmakers didn't refer to that explicitly on Thursday.
Church leaders, however, criticized the decision. The country's top Roman Catholic bishop, Archbishop Robert Zoellitsch, said that "the selection of human embryos violates the precept of respect for human dignity" and Lutheran church leader Nikolaus Schneider said he would have liked greater restrictions.
Thursday's debate centered squarely on the morality of the procedure, a test done to pick the best embryos, rather than its medical merits — which researchers say have largely been a disappointment.
Doctors had assumed the test would improve pregnancy rates, but studies showed that women who had their embryos tested were actually less likely to become pregnant, probably because scientists still can't accurately predict which embryos will succeed.
A study in its early stages presented this week at a European fertility conference in Stockholm suggested that embryos which look problematic three days after fertilization can fix themselves by day five. Many embryos created by IVF are implanted after three days, although doctors are increasingly waiting until day five if possible.
The German motion refers to tests removing one to two cells out of an embryo about three days after its fertilization — when it typically has about eight cells — to see whether it looks abnormal.
Some experts say that is too early and jeopardizes the embryo's future development.