Research ArticleGUT MICROBIOTA

Increased weight gain by C-section: Functional significance of the primordial microbiome

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Science Advances  11 Oct 2017:
Vol. 3, no. 10, eaao1874
DOI: 10.1126/sciadv.aao1874

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  • Editorial Correction to Dominguez-Bello "Response to Torgerson eLetter, Increased weight gain by C-section: Functional significance of the primordial microbiome"

    Note from the Editor:

    There was an editorial error in the Dominguez-Bello response.  The second to last sentence should read "females" not males. The correct version should read:

    "Thus, multivariate analysis that considers the hierarchical nature of this data, shows that body weight is is increased in C-section-fostered animals, with stronger phenotypes in females. We are currently performing experiments that segregate the effects of other factors on the phenotype."

     

    Please excuse the error.

    -The Science Advances Editorial Team

    Competing Interests: None declared.
  • RE: Response to Torgerson eLetter, Increased weight gain by C-section: Functional significance of the primordial microbiome

    We thank Drs. David Torgerson and Catherine Hewit for their comments to our manuscript. In the referred study, pregnant mice were randomly assigned to have a C-section or not. Statistical analyses were performed to account for clustering of outcomes among siblings in the 11 clusters at ages 3, 4, 9, 12 and 15 weeks confirmed increased body weight in C-section born in relation to vaginally born. For females, the differences were significant using ANOVA2 at ages 9 weeks (p<0.01), 12 and 15 weeks (p<0.001); for males, significance was observed only at week 3 and 4 of age (p<0.01). Additionally, t-Test analysis using cluster level means, also showed significantly higher body weight in females at ages 3, 6, 9, 12, 13, 14, 15 weeks (p<0.05) and in males at 3 weeks of age only. Thus, multivariate analysis that considers the hierarchical nature of this data, shows that body weight is is increased in C-section-fostered animals, with stronger phenotypes in males. We are currently performing experiments that segregate the effects of other factors on the phenotype.

    Competing Interests: None declared.
  • RE: Inappropriate statistical analysis?

    Editor: In this paper the authors do not state whether the pregnant mice were randomly assigned to have a C-Section or not, without which selection bias can be introduced. Furthermore, the statistical analysis does not seem to take into account the clustering of outcomes among siblings, without which the standard errors and p values are too small. The resampling approach utilised does not specify if it accounted for the hierarchical nature of the data which could lead to further misrepresentation. The statistical approach to dealing with clustered data has been described as far back as 1940 [1]. Re-analysis taking into account this source of clustering is needed to get a valid analysis. Unfortunately, there are relatively few clusters (i.e, 11 in total) so sophisticated analyses are not possible. However, the authors should repeat their analysis using cluster level means [2] (i.e., calculating the mean weights of all the pups born to their mother) and compare these using a t-test (i.e, the total mean weights of pups born to C-section mice (n = 5) vs the total mean weights of control mother’s pups (n= 6). This will be a valid analysis. A worked example, in education, demonstrating the correct approach to analysing such data can be found here (https://www-users.york.ac.uk/~mb55/clust/incent.htm). Additionally, there is likely to be other sources of data clustering if the C-section sibling mice were fostered by...

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    Competing Interests: None declared.