In the following article[1] the authors have identified that a publication was missing from one of their meta-analyses. They identified four publications which reported ‘major congenital malformations’, where five should have been identified. The missing publication was that of Blais et al.,[2] a retrospective study which reported an increased risk of both any congenital malformations (odds ratio [OR] 1.30, 95% confidence interval [CI] 1.20–1.40) and major congenital malformations (OR 1.34, 95% CI 1.22–1.47) among women with asthma compared to women without asthma. The data for the outcome ‘any congenital malformations’ was included in the meta-analysis. However, the data on ‘major malformations’ was inadvertently not included in the analysis.

The authors have repeated the meta-analysis with the data from Blais et al. included, and the overall result was unchanged. Initially they reported that maternal asthma was not associated with an increased risk of major congenital malformations (RR 1.31, 95% CI [0.57, 3.02])[1]. With the additional study included, maternal asthma was still not associated with an increased risk of major congenital malformations (RR 1.18, 95% CI [0.75, 1.84]). Since Blais’ study was very large, the number of major malformations included increased from 119 in the asthma group to 901, and from 66 in the control group to 1313.


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  2. References
  • 1
    Murphy VE, Wang G, Namazy JA, Powell H, Gibson PG, Chambers C, et al. The risk of congenital malformations, perinatal mortality and neonatal hospitalisation among pregnant women with asthma: a systematic review and meta-analysis. BJOG 2013;120:81222.
  • 2
    Blais L, Kettani F, Elftouh N, Forget A. Effect of maternal asthma on the risk of specific congenital malformations: a population-based cohort study. Birth Defects Res A Clin Mol Teratol Clin Mol Teratol 2010;88:21622.