RT Journal Article SR Electronic T1 Social media and advertising natural contraception to young women: the case for clarity and transparency with reference to the example of ‘Natural Cycles’ JF BMJ Sexual & Reproductive Health JO BMJ Sex Reprod Health FD British Medical Journal Publishing Group SP bmjsrh-2018-200110 DO 10.1136/bmjsrh-2018-200110 A1 Amy Hough A1 Maggie Bryce A1 Simon Forrest YR 2018 UL http://jfprhc.bmj.com/content/early/2018/07/21/bmjsrh-2018-200110.abstract AB