Scientists call for review of UK’s 14-day rule on embryo research

The restriction of studies of early life to after two weeks has left a ‘black box’ period from two to around four weeks of development that has never been directly studied. Photograph: Alamy

Scientists are calling for a review of the 14-day rule on embryo research, saying that extending the limit could help uncover the causes of recurrent miscarriage and congenital conditions.

Until now, scientists studying the earliest stages of life have been restricted to cultivating embryos up to the equivalent of 14 days of development. They can then pick up the path of development several weeks later, on pregnancy scans and from material donated from terminations.