Effects of multiple courses of antenatal steroids are uncertain

Editor—Spencer and Neales highlight the uncertainty surrounding the risks and benefits of giving multiple courses of antenatal steroids to pregnant women at risk of preterm delivery.¹ They refer to our survey of practice carried out in 1997,² and it would be helpful to clarify some of the figures that they quote.

Firstly, the survey did not find that 98% of women at risk of preterm birth receive prophylactic antenatal corticosteroids; rather, it found that 98% of obstetric units prescribe repeated courses for at least some women at risk.

Secondly, the meaning of the statement that “74% of UK maternity units give repeated doses on a weekly basis” may not be clear. The survey found that among units that use multiple courses the interval between repeated courses was seven days in 74% of units. Other units used intervals of 10-14 days.

Spencer and Neales discuss the evidence from observational studies for beneficial and harmful effects of multiple courses of antenatal steroids. These studies may be open to serious biases. The number of courses that an infant is exposed to will be influenced by the gestational age at birth; infants exposed to more courses will tend to be born at greater gestational ages, which will tend to improve their outcomes. Conversely, infants exposed to multiple courses may remain in a high risk situation for longer and hence have poorer outcomes. Observational studies may be biased in either direction, which may explain some of the inconsistency among their results.

This editorial and another published recently³ highlight the lack of any randomised controlled trials of single versus multiple courses of antenatal steroids. Several trials are planned or in progress, and until they are completed—including evaluation of both short term outcomes (death and the respiratory distress syndrome) and children's long term neurodevelopment—the uncertainty about the risks and benefits of multiple courses will remain. The best policy for obstetricians would therefore be to contribute to resolving this issue by participating in the current trials.

In the United Kingdom the Perinatal Trials Service has recently started a large trial of single versus multiple courses of antenatal steroids (trial of the effects of antenatal multiple courses of steroids versus a single course (TEAMS)); the initial part of this trial has been funded by Action Research. Any obstetric units that would like to participate should contact the trial's coordinating centre by telephone (01865 227122) or email (teams@perinat.ox.ac.uk).