Transferred. Then you wait and see whether the embryo implants.
A twin pregnancy is automatically a high risk pregnancy. Greater risks to the mother, and greater risks to the foetuses, including miscarriage and prematurity. When a woman with fertility issues goes through with IVF, indeed sometimes more than one embryo is transferred, in the hope that one implants and initiates a pregnancy. That's because the odds of pregnancy for her are so poor if only one embryo at a time is transferred. Sometimes this results in multiple embryos implanting, and it is not a desirable outcome. As I said before, a twin pregnancy is high-risk. Reproductive endocrinologists want to avoid it. If you don't understand why, take a trip round an NICU.
This however is a woman without fertility issues, who was selected because she didn't have fertility issues. Only one embryo needed to be transferred for good odds of a pregnancy. Multiple embryos were transferred because the commissioning couple wanted to have twins.
It's irresponsible. From the first, they've chosen to gamble with the babies' health and they lost: the babies were born weeks and weeks early.