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Association of maternal body mass index with intellectual disability risk
  1. Priscilla Ming Yi Lee1,
  2. Lap Ah Tse1,
  3. Krisztina D László2,
  4. Dang Wei2,
  5. YongFu Yu3,
  6. Jiong Li3
  1. 1 Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong Faculty of Medicine, Hong Kong, Hong Kong
  2. 2 Department of Global Public Health, Karolinska Institute, Stockholm, Sweden
  3. 3 Department of Clinical Medicine-Department of Clinical Epidemiology, Aarhus Universitet, Aarhus, Midtjylland, Denmark
  1. Correspondence to Professor Lap Ah Tse, Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, Hong Kong; shelly{at}cuhk.edu.hk

Abstract

Objectives The study aimed to investigate the association between maternal body mass index (BMI) in early pregnancy and children’s intellectual disability (ID) risk in the absence of chromosomal disorders, neurofibromatosis and tuberous sclerosis, taking adverse birth outcomes, maternal hypertension/diabetes and maternal socioeconomic status into consideration.

Methods We conducted a cohort study of singletons without common genetic defects born in Sweden during 1992–2006, and followed them from birth until 31 December 2014 (n=1 186 836). Cox proportional hazards models were used to analyse the association between maternal BMI in early pregnancy and the risk of offspring’s ID.

Results The risk of ID was higher in children born to mothers who were underweight (HR=1.21, 95% CI=1.07 to 1.36), overweight (HR=1.28, 95% CI=1.21 to 1.34) or had obesity class I (HR=1.63, 95% CI=1.53 to 1.74), obesity class II (HR=2.08, 95% CI=1.88 to 2.30) and obesity class III (HR=2.31, 95% CI=1.46 to 3.65) than in children born to normal weight mothers. Results remained consistent after excluding children with adverse birth outcome or born to mothers with gestational hypertension/diabetes. Analysis stratified by maternal education and annual household income showed that the association between maternal underweight and children’s ID risk was attenuated among children of mothers with tertiary education or with high income.

Conclusions Our findings suggest that maternal underweight or overweight/obesity in early pregnancy was associated with the development of ID in their offspring. This association was independent of the effect of adverse birth outcomes and maternal hypertension/diabetes. High socioeconomic status may attenuate the risk of ID among children of underweight mothers. This study highlights the importance of improving health education before conception to reduce children’s ID risk.

  • epidemiology
  • child psychiatry
  • obesity
  • neurology

Data availability statement

Data are available on reasonable request. The results and materials described in the article, and the relevant data related to maternal body mass index in early pregnancy that was used in this article, are available from the corresponding author on reasonable request.

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Data availability statement

Data are available on reasonable request. The results and materials described in the article, and the relevant data related to maternal body mass index in early pregnancy that was used in this article, are available from the corresponding author on reasonable request.

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Footnotes

  • Contributors LAT supervised and gave ideas on this present study. JL oversaw this present study and revised the manuscript. PMYL reviewed the literature, analysed the data and drafted the manuscript under the supervision of LAT and JL. KDL commented and revised the current manuscript. DW support in cleaning the data. YFY helped in analysing the data and gave suggestion on the current manuscript. All authors contributed to the development of this study and approved the final version of this manuscript.

  • Funding This study was supported by grants from the Danish Council for Independent Research and Independent Research Fund Denmark (DFF-6110-00019B and 9039-00010B); grants from the Nordic Cancer Union (R275-A15770); a grant from the Karen Elise Jensens Fond (2016); a grant from Novo Nordisk Fonden (NNF18OC0052029) and National Natural Science Foundation of China (82073570).

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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