old licensed menstrual light/absent rx in US
Seasonale 2003 – 4 periods a year
Lybrel 2007 – no periods at all
https://sitn.hms.harvard.edu/flash/2008/issue40/ – logical progression

Long v interesting essay on the prehistory 2015
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4462239/

clearly being prescribed for ‘heavy periods’ / regulation rather than contraception in Ireland

https://www.tandfonline.com/doi/full/10.1080/09612025.2020.1833495

John  Rock 

https://jamanetwork.com/journals/jama/article-abstract/664981

cochrane review
https://www.cochrane.org/CD004695/FERTILREG_combined-hormonal-contraceptives-taken-extended-regimens-more-28-days-compare-favorably-traditional

safety assessment
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2621397/

Julia’s contraceptive website
https://www.contraceptionchoices.org/

change in guidance to allow continuous use

https://www.fsrh.org/standards-and-guidance/documents/combined-hormonal-contraception/