Sir,

The authors have erroneously concluded that maternal smoking reduced the incidence of severe ROP, when in fact only 1/27 (or 4%) reported maternal smoking and 26/27 (or 96%) did not report any maternal smoking. Lack of evidence does not equate to evidence of an effect (or association in this case). In the non-severe ROP group, 15/59 (or 25%) mothers reported maternal smoking and the authors did not report a reduction in the incidence of non-severe ROP. Re-analysis of the reported data (development of non-severe ROP; smokers 15/59 versus non-smokers 44/59) provides the following: RR 0.12, 95% CI 0.05–0.27 (P<0.00001), favouring non-smokers with a reduction in the incidence of non-severe ROP of 88%.

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