No Link Found Between Autism and Maternal Fish Ingested During Pregnancy Interview with:
“Fish” by Dhruvaraj S is licensed under CC BY 2.0Dr Caroline M Taylor
Wellcome Trust Research Fellow
Centre for Child and Adolescent Health
Bristol Medical School, University of Bristol
Oakfield House, Oakfield Grove, Bristol What is the background for this study?

Response: Mercury is a toxic metal that is widespread in the environment. In pregnancy, mercury in the mother’ bloodstream is transferred through the placenta to the fetus, where is can affect development of the nervous system. Mercury from vaccines has been the focus of attention particularly in regard to a link with autism in children. However, the amount of mercury used in the vaccines is small in comparison with mercury from the diet and atmospheric pollution, and in the EU at least, childhood vaccines no longer contain this preservative. The fear that mercury is linked to autism has persisted, despite increasing evidence that this is not the case.

The aim of our study was to look at mercury from the diet rather than vaccines – specifically from fish – in pregnant women. We measured the women’s mercury levels in their blood and asked them about how much fish they ate. We then followed up their children for 9 years and recorded how many of them had autism diagnosed within that time. We also measured how many of them had autist traits by measuring their social and communication difficulties.  The data were part of the Children of the 90s study (Avon Longitudinal Study of Parents and Children – ALSPAC), which is based in Bristol, UK. What are the main findings?

Response: Our main finding was that even though mothers who ate fish in pregnancy had higher mercury levels in their blood, there was no increase in the chance that her child would have autism or autistic traits. Indeed, the score for one of the traits, social cognition (for example, awareness of other people’s feelings), was likely to be worse in the child if the mother had not eaten fish in pregnancy. What should readers take away from your report? 

Response: Pregnant women should be reassured that eating fish in pregnancy is positively beneficial for the baby and is very unlikely to be a cause of autism. In common with many other countries, the UK has national guidelines in eating fish in pregnancy. The main recommendation is that women should eat at least two portions of fish per week, with one of them being an oily fish. Taking all of our research into account, in which we have looked at several aspects of child development in relation to the mother’s mercury levels, we have called for this recommendation to be made clearer and more prominent, rather than an emphasis on fish species to limit or avoid. We would like to encourage women to eat fish during pregnancy so as not to miss out on the beneficial nutrients contained in fish.

Disclosures: Dr Caroline Taylor receives funding from the Wellcome Trust (grant no. 104077/Z/14/Z) 


Jean Golding, Dheeraj Rai, Steven Gregory, Genette Ellis, Alan Emond, Yasmin Iles-Caven, Joseph Hibbeln, Caroline Taylor. Prenatal mercury exposure and features of autism: a prospective population study. Molecular Autism, 2018; 9 (1) DOI: 10.1186/s13229-018-0215-7




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