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Research article
Deborah L. O’Connor
University of Toronto
Corresponding Author
ORCiD: https://orcid.org/0000-0001-6331-091X
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Background: Few studies have examined how maternal body mass index (BMI), mode of delivery and ethnicity affect the microbial composition of human milk and none have examined associations with maternal metabolic status. Given the high prevalence of maternal adiposity and impaired glucose metabolism, and the importance of human milk in the colonization of the infant gut, we systematically investigated the associations between these maternal factors and milk microbial composition and functionality.
Methods: Women ≥20 years were recruited during pregnancy and milk samples were collected at 3 months post-partum (NCT01405547). Demographic data, weight, height, and a 3-hour oral glucose tolerance test were conducted at 30 (95% CI: 25-33) weeks gestation. Metagenomic DNA extraction and 16S ribosomal RNA gene sequencing of the V4 hypervariable region (Illumina MiSeq) was carried out on 113 milk samples.
Results: Multivariable linear regression analyses demonstrated no significant associations between maternal characteristics (maternal BMI [pre-pregnancy, 3 months post-partum], glucose tolerance, mode of delivery and ethnicity) and microbiota alpha-diversity; however, pre-pregnancy BMI was associated with human milk beta-diversity (Bray-Curtis p=0.040). Women with a pre-pregnancy BMI >30 kg/m2 (obese) had a greater incidence of Bacteroidetes (incidence rate ratio [IRR]: 3.70 [95% CI: 1.61-8.48]) and a reduced incidence of Proteobacteria (0.62 [0.43-0.90]), compared to overweight women (BMI 25.0-29.9 kg/m2) as assessed by multivariable Poisson regression. Increased incidence of Gemella was observed among overweight (versus healthy) mothers with gestational diabetes (5.96 [1.85-19.21]) and obese (versus healthy) mothers with impaired glucose tolerance (4.04 [1.63-10.01]). An increased incidence of Brevundimonas (16.70 [5.99-46.57]) was found in the milk of women who underwent an unscheduled C-section versus vaginal delivery. Lastly, functional gene inference demonstrated that obesity was associated with increased abundance of genes encoding for the biosynthesis of secondary metabolites in milk (coefficient=0.00028, p=0.0070).
Conclusions: Mother’s milk has a diverse microbiota of which its diversity and differential abundance appear associated with maternal body size, glucose tolerance status, mode of delivery, and ethnicity. Further research is warranted to determine whether this variability in the milk microbiota impacts colonization of the infant gut.
Keywords
Mother’s milk, microbiota, body mass index, gestational diabetes, impaired glucose tolerance, mode of delivery, vaginal delivery, Caesarean delivery, ethnicity, microbiome
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View the published article at BMC Microbiology.
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Editorial decision: Major revision
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Reviewer #1 agreed
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See the published version of this preprint at BMC Microbiology.
This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research article
Deborah L. O’Connor
University of Toronto
Corresponding Author
ORCiD: https://orcid.org/0000-0001-6331-091X
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Published
View the published article at BMC Microbiology.
Version 1
Posted 13 Mar, 2020
No community comments so far
Editorial decision: Major revision
On 21 Apr, 2020
Review #1 received
Received 05 Jan, 2020
Reviewers invited
Invitations sent on 09 Dec, 2019
Reviewer #1 agreed
On 09 Dec, 2019
Editor assigned
On 02 Dec, 2019
Submission checks complete
On 01 Dec, 2019
Editor invited
On 01 Dec, 2019
First submitted
On 29 Nov, 2019
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
View the published article at BMC Microbiology.
Background: Few studies have examined how maternal body mass index (BMI), mode of delivery and ethnicity affect the microbial composition of human milk and none have examined associations with maternal metabolic status. Given the high prevalence of maternal adiposity and impaired glucose metabolism, and the importance of human milk in the colonization of the infant gut, we systematically investigated the associations between these maternal factors and milk microbial composition and functionality.
Methods: Women ≥20 years were recruited during pregnancy and milk samples were collected at 3 months post-partum (NCT01405547). Demographic data, weight, height, and a 3-hour oral glucose tolerance test were conducted at 30 (95% CI: 25-33) weeks gestation. Metagenomic DNA extraction and 16S ribosomal RNA gene sequencing of the V4 hypervariable region (Illumina MiSeq) was carried out on 113 milk samples.
Results: Multivariable linear regression analyses demonstrated no significant associations between maternal characteristics (maternal BMI [pre-pregnancy, 3 months post-partum], glucose tolerance, mode of delivery and ethnicity) and microbiota alpha-diversity; however, pre-pregnancy BMI was associated with human milk beta-diversity (Bray-Curtis p=0.040). Women with a pre-pregnancy BMI >30 kg/m2 (obese) had a greater incidence of Bacteroidetes (incidence rate ratio [IRR]: 3.70 [95% CI: 1.61-8.48]) and a reduced incidence of Proteobacteria (0.62 [0.43-0.90]), compared to overweight women (BMI 25.0-29.9 kg/m2) as assessed by multivariable Poisson regression. Increased incidence of Gemella was observed among overweight (versus healthy) mothers with gestational diabetes (5.96 [1.85-19.21]) and obese (versus healthy) mothers with impaired glucose tolerance (4.04 [1.63-10.01]). An increased incidence of Brevundimonas (16.70 [5.99-46.57]) was found in the milk of women who underwent an unscheduled C-section versus vaginal delivery. Lastly, functional gene inference demonstrated that obesity was associated with increased abundance of genes encoding for the biosynthesis of secondary metabolites in milk (coefficient=0.00028, p=0.0070).
Conclusions: Mother’s milk has a diverse microbiota of which its diversity and differential abundance appear associated with maternal body size, glucose tolerance status, mode of delivery, and ethnicity. Further research is warranted to determine whether this variability in the milk microbiota impacts colonization of the infant gut.
Figure 1
Figure 2
Figure 3
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