1. Abortion incidence between 1990 and 2014: global, regional, and subregional levels and trends;Sedgh;Lancet,2016
2. Who presents more than once? Repeat abortion among women in Britain;Stone;J Fam Plann Reprod Health Care,2011
3. Department of Health Abortion Statistics, England and Wales 2015 https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/570040/Updated_Abortion_Statistics_2015.pdf
4. ISD Scotland. Scottish Health Statistics Abortions 2015 Sexual Health, Abortions http://www.isdscotland.org/Health-Topics/Sexual-Health/Abortions/
5. Office for National Statistics Conceptions in England and Wales 2014 https://www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/conceptionandfertilityrates/bulletins/conceptionstatistics/2014#conceptions-leading-to-abortion-by-age