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Secondary prevention: a new era for postpartum haemorrhage?

The study by Raghavan et al. examines a new concept in PPH management, that of ‘secondary prevention’. The concept is that it may be safe to defer prophylactic uterotonics so that only those women who reach 350 ml receive treatment (as compared with at the traditional level of 500 ml). If safe, this strategy is likely to be cheaper and more acceptable to women. In truth, in many previous studies of PPH prophylaxis, actual blood loss was not measured and so the level at which women were really treated is not known. But an individual patient data analysis of several large randomised trials shows that those individuals who received PPH treatment frequently had a final blood loss of much less than 500 ml (N. Aflaifel, PhD Thesis, University of Liverpool), and this fits with observations from simulation studies. Clinicians commonly start to treat PPH as soon as they consider it ‘more than normal’ and so often don’t wait for the woman to lose 500 ml. If this is also true in clinical trials, then the ‘physiological management’ arm in previous studies might have been very similar to this one with treatment being started early. Intriguingly, the halving of PPH rates (both at 350 and 500 ml) seen in this study is very similar to the results of those previous active management studies, albeit with much smaller numbers. But the extremely low rate of PPH in this study meant that it turned out to be underpowered. Sadly, therefore, this study will need to be repeated in a population with higher PPH rates before we can sure that the strategy is safe. But why was the PPH rate so low? It is unlikely to be simply due to both interventions being very effective—indeed only 4.7% of women in the secondary prevention arm reached 350 ml despite physiological management up to that point. But it may reflect the extensive list of exclusion criteria that ensured that only low risk women in normal labour were included. Low risk women typically have low rates of PPH and so may not be the most important focus for public health strategies (Weeks AD, Neilson JP. BMJ 2015;351:h3251). If we are to make inroads into the huge global death toll from PPH, future studies need to concentrate on those at the highest risk: those with placenta praevia, abruption, emergency CS, and intrapartum complications. This study moves the understanding of PPH care forward considerably. Not because it provides a definitive answer but because it dares question whether active management is always necessary in low and middle income countries. The finding of low rates of PPH in carefully selected normal births along with the encouraging outcomes of ‘secondary prevention’ is an important move towards personalising PPH care. I would be prepared to bet that it is not long before ‘secondary prevention’ becomes the standard of care for low risk women worldwide, and the public health focus is turned instead on those at highest risk.