The Free Birth Society (FBS) is a multimillion-dollar business that promotes an extreme version of free birth, meaning women giving birth without medical assistance. The Guardian can now reveal that the organisation has been linked to dozens of cases of maternal harm and baby deaths around the world. After a year-long investigation, Sirin Kale and Lucy Osborne explain why some women they interviewed found FBS’s views so appealing, and why medical professionals say their claims about birth are dangerous

• The Birth Keepers: I choose this – episode one