Background/Objective Offspring s optimal neurodevelopment depends on maternal dietary lipids supply during the perinatal period. Dairy products are an important source of fat in Western diets. This study aimed at examining the associations between maternal dairy fat intake during pregnancy, evaluated through biomarkers in perinatal biofluids (C15:0 and C17:0) and child s cognitive outcomes. Subjects/Methods Participants (N up to 1200) were French mother-child pairs from the EDEN cohort study. Biomarkers were assessed in the following biofluids: maternal red blood cells (RBC) membrane at 24 weeks of gestation, cord RBC membrane and colostrum. Cognitive outcomes were language abilities scores at ages 2 and 3 years and overall cognitive development scores at ages 3 and 5-6 years. Associations were assessed using multiple linear regression models adjusted for factors related to family socioeconomic context, maternal lifestyle and healthy diet score. Interaction of any breastfeeding duration on the associations with dairy fat biomarkers in colostrum was studied. Results Positive associations were observed between levels of C17:0 in cord RBC and C15:0 in maternal RBC with language abilities. In children breastfed for at least 6 months, C15:0 level in colostrum was positively associated with language abilities at age 3 years and overall cognitive development at ages 3 and 5-6 years whereas C17:0 level was only associated with overall cognitive development at age 3 years. Conclusion Our results suggest that maternal higher intake of dairy fat during perinatal period could be potentially associated with offspring s better cognitive development. These pioneering results call for external validation to challenge their causality.

The authors have declared no competing interest.

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This study was sponsored by French Dairy Interbranch Organisation (CNIEL). CNIEL was involved in the study hypothesis and provided few inputs on the interpretation of the results but was not involved in the study design, execution and analysis. The EDEN cohort study was financed by the Foundation for Medical Research, National Agency for Research (ANR), National Institute for Research in Public Health, French Ministry of Health, French Ministry of Research, Inserm Bone and Joint Diseases National Research and Human Nutrition National Research Programs, Paris Sud University, Nestle, French National Institute for Population Health Surveillance, French National Institute for Health Education, the European Union FP7 programs (FP7/2007 2013, HELIX, ESCAPE, ENRIECO, Medall projects), Diabetes National Research Program (through a collaboration with the French Association of Diabetic Patients), French Agency for Environmental Health Safety (now ANSES), Mutuelle Generale de l Education Nationale, French National Agency for Food Safety, and the French speaking association for the study of diabetes and metabolism. Biological analyses of colostrum samples were funded by the PremUp foundation (French foundation for scientific cooperation in connection with pregnancy and prematurity) and the Groupe Lipides Nutrition. Biological analyses of red blood cell membrane were funded by the Institut Danone France and FRM (Prix IDF/FRM pour les Sciences de l Alimentation 2015). All funders (except CNIEL with aforementioned involvement) had no influence of any kind on the study hypothesis/design, execution, analysis or interpretation.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The EDEN mother-child cohort study was approved by the ethics committee of Kremlin Bicêtre (CPP reference 02-70, December 2002; CCTIRS reference 02-189, July 2002) and the National Data Protection Authority ("Commission Nationale de l’Informatique et des Libertés", CNIL reference 902267, December 2002).

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I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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The data underlying the findings cannot be made freely available for ethical and legal restrictions imposed, because this study includes a substantial number of variables that, together, could be used to re-identify the participants based on a few key characteristics and then be used to have access to other personal data. Therefore, the French ethics authority strictly forbids making these data freely available. However, they can be obtained upon request from the EDEN principal investigator. Readers may contact barbara.heude@inserm.fr to request the data. The analytic code will be made available upon request pending application and approval.