Over the last 30 years anti-D, or Rhogam as it is known in the USA, has become accepted as being routinely advisable for rhesus negative women. Yet the question remains that - if women's bodies are designed to give birth without intervention for the majority of the time - why is this necessary? This text explores the paradox between physiological birth and the routine "need" for anti-D and highlights evidence which may throw light on this paradox. Are women's bodies really fallible, or could some women's need for anti-D be caused by medical intervention in childbirth? Do women being offered anti-D know that this is a blood product which may carry attendent risk? What information do women need in order to decied whether or not they will have anti-D? This text discusses these issues.