Footnotes

• Contributors MHZ and VR were responsible for data analysis with intellectual contribution from AJ and BMK. MHZ and VR drafted the article. All authors contributed to the conception and design of the paper, interpretation of data, critical revisions contributing to the intellectual content and approval of the final version of the manuscript.

• Funding Maternal Infant Child and Youth Research Network (MICYRN); Canadian Partnership Against Cancer (CPAC).

• Competing interests None declared.

• Provenance and peer review Commissioned; externally peer reviewed.