LAUSR

INTRODUCTION The Fifty Shades of Grey (FSOG) trilogy were publicised by the media as inflaming increased coital activity, and that this would result a baby boom. Furthermore, increased coital activity skews the sex ratio at birth (M/T) toward male births. This study was carried out in order to ascertain whether there were any spikes in total births or in M/T in the United States (US) circa nine months following the FSOG books. METHODS Monthly male and female births for the US were obtained directly from the website of the Centre for Disease Control (01/2007-12/2015). RESULTS This study analysed 36,499,163 live births (M/T 0.5117, 95% CI 0.5116-0.5119). There are no discernible spikes in total births or M/T at annual level, or circa nine months after FSOG book releases i.e. 04/2012 and 01/2013. DISCUSSION The absence of spikes in births or M/T may have been due to exaggeration of the FSOG effect, it may only have provoked planned pregnancies, or modern contraception was sufficiently effective to prevent extra conceptions. The media build-up may also have stimulated a Hawthorne effect, with FSOG-affected individuals employing effective contraception. This study highlights the importance of measurement of cause and effect since anticipated results may not always ensue from events.