A leading centre for pre-implantation genetic diagnosis, the Reproductive Institute of Chicago, has concluded that extracting a cell from an eight-cell embryo to test it for genetic disorders, does not cause birth defects. In research published in the journal Fertility and Sterility, the clinic said that PGD babies are no more likely to suffer birth defects than babies born after natural pregnancies. The news supports a recent decision by the UK’s fertility watchdog, the Human Fertilisation and Embryology Authority, to allow PGD to create tissue matched “saviour siblings”.

About 1,000 babies around the world have been born with the help of PGD since it was first used experimentally around 1990. Like other IVF procedures, its effects were never studied in animal models or in human clinical trials before it became a standard procedure. Although the HFEA now says that the US study should reassure parents that the test will not harm their babies, it will probably be news to many that the HFEA and IVF scientists had harboured any concerns in the first place. Since the research was done by the same institute which first used the procedure and has subsequently done more of it than any other clinic, more results will probably be needed to allay all misgivings about the technique.