Antibiotics in pre-term labour

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Fair tests of treatments with hoped-for beneficial effects, and which are assumed to be harmless, can show that neither is true. Doctors prescribe treatments with the best of intentions, particularly when they may offer hope in a desperate situation. For example, a theory suggested that ‘silent’ (sub-clinical) infection might trigger early labour and preterm delivery.

The theory led doctors to prescribe antibiotics for some pregnant women in the hope that this might help to prolong pregnancy. No one seriously thought that using antibiotics in this way would cause any serious problems. Indeed, there is some evidence that women themselves were keen to have antibiotics – in a spirit of ‘let’s try this; it can’t do any harm’.

When a fair test of this treatment was eventually done, the results had clear clinical implications. For a start, no benefits were identified. On top of that, long-term follow-up of the babies in the study showed that those who had been exposed to antibiotics were more likely than those in the comparison groups to have cerebral palsy and problems with speech, vision, and walking. These risks of antibiotics had remained unrecognized over the decades that antibiotics had been prescribed to women, but without adequate evidence from fair tests about their effects.

As often happens, those who were given an inadequately evaluated treatment in ‘normal’ clinical practice were more likely to be harmed than those given the same treatment prescribed in a research context. Put another way, people were generally more at risk when they were not taking the drugs as part of a fair test. [17], [18], [19]