In an effort to reduce the number of “test tube” twins and triplets, Britain’s regulator of fertility treatment told clinics Tuesday they no longer can implant more than two embryos in women under 40.
The Human Fertilization and Embryo Authority set a limit of three embryos for women over 40, who have a harder time getting pregnant.
The new regulation reflects a general trend across Europe and elsewhere to reduce the number of embryos in fertility treatment.
Doctors have long believed implanting more embryos would improve the chances of a successful pregnancy, but that practice has also led to more multiple births, which are risky for mother and baby.
Recent studies, however, show that the chances of getting pregnant with one embryo can be just as good as with two or three embryos.
“Women are designed to have healthy babies, one at a time, and with natural conception this is what usually happens. But over half of babies born as a result of fertility treatment are twins or triplets,” said Suzi Leather, chairwoman of the British regulating agency.
“The aim ... is to bring the number of multiple births from fertility treatment closer to that which occurs naturally.”
Experts believe the future of fertility treatment is to use one embryo, but select it more carefully.
In some countries, such as Belgium, Sweden and Finland, fertility treatments using a single embryo already are common practice.
Among developed Western countries, the United States has been slowest to adopt the new thinking, said European fertility expert Dr. Karl Nygren, a professor of obstetrics and gynecology at Sofiahemmet Hospital in Stockholm, Sweden.
American guidelines recommend the transfer of between three and five embryos, depending on the mother’s age.
“They are also coming along, but it goes more slowly. It’s not that they are uneducated, it’s that fertility treatment there is so expensive,” Nygren said.
In the United States, patients particularly want to maximize their chances of a quick pregnancy to keep costs down, while their doctors are anxious to show results in the competitive fertility field, experts say.