BMJ  2003;326:1268-1269 (7 June), doi:10.1136/bmj.326.7401.1268-b

Letter

Consumption of coffee during pregnancy

Data do not support claim

The first 150 words of the full text of this article appear below.

EDITOR—Wisborg et al found an association between maternal coffee consumption and risk of stillbirth, and claim that after adjustment for potential confounding factors the association remained significant.¹ However, I am not convinced that the data they present support that claim.

The claim of a significant association seems to be based on the statistical significance for the odds ratio that compares the highest consumption group with the zero consumption group. This odds ratio is in any case only marginally significant at the 5% level, as the 95% confidence interval extends as far as 1. More importantly, Wisborg et al do not present the results of an overall test of differing risk of stillbirth among all the coffee consumption groups.

From a statistical point of view, it is not good practice to rely on pairwise comparisons between specific groups if the overall group effect is not significant. We are not . . . [Full text of this article]

Dianthus Medical Limited, London SW19 3TZ ajacobs@dianthus.co.uk

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Maternal consumption of coffee during pregnancy and stillbirth and infant death in first year of life: prospective study

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