‘We’re running out of room for embryos’: inside IVF’s big problem

Marta Jansa Perez lifts a blue plastic lid off the metal tank and a cloud of nitrogen vapour billows upwards. “We have space in here for the next few years, but demand is ramping up,” she says. “We might run out of room sooner or later.” Perez, 56, is director of embryology at Bridge Clinic, a private fertility clinic tucked away behind a newsagent’s near the British Library in London. Just as the library has had to build vast underground vaults — and a giant repository in Yorkshire — to store its rapidly expanding collection of books, fertility clinics such as Perez’s are having to find their own ingenious solutions to a uniquely 21st-century storage problem.

Just a few decades ago “test tube babies” were