In a new study, scientists have found no link between consuming fish during pregnancy and an increased risk of autism in children. A diet containing fish could even be beneficial for a foetus’s development of a healthy nervous system, according to the research.
For decades, exposure to mercury and other heavy metals in the womb or in early childhood has been suspected of causing autism in children. In a new study, however, scientists at the University of Bristol in the United Kingdom, have uncovered evidence that the omega fatty acids found in fish provide more benefits to a developing foetus than risks.
“The advice on eating fish when pregnant is complicated and overwhelming. There is now a body of evidence to support a simpler and clearer approach that maximises the health benefits of fish,” Dr Caroline Taylor, a Wellcome Trust Research Fellow at the University of Bristol who contributed to the research, said in a statement.
In one of the largest longitudinal studies to date, University of Bristol researchers analysed data from nearly 4,500 pregnancies. The study, published in the journal Molecular Autism, was part of a 20-year-long, on-going research project to determine what types of long-term effects lifestyle and environment may have on childhood development.
Researchers measured the women’s trace mercury levels through blood samples and analysed mercury exposure through reported information regarding fish consumption and mercury alloy dental fillings.
The team found no association between the mothers’ mercury levels and autism or autistic traits in their children up to age 11. According to the findings, only 45 of the 177 pregnancies that led to a child with autism spectrum disorder had detectable levels of mercury. The study also found that the mean blood level of mercury was similar to that of the pregnancies that did not result in a child with autism.
“Our findings further endorse the safety of eating fish during pregnancy,” Professor Jean Golding, lead author of the study, said in a statement. “Importantly we’ve found no evidence at all to support claims that mercury is involved in the development of autism or autistic traits.”
Researchers emphasised that the benefits of eating fish during pregnancy outweigh the risks. Eating “at least two fish meals a week” during pregnancy provides “a good nutritional start to life,” according to Golding.
“All species of fish contain traces of mercury, which can harm brain development, but we’ve found that the health benefits of fish, probably from nutrients such as vitamin D, omega-3 fatty acids, selenium and iodine, outweigh the risks from mercury,” explained Taylor.
Carol Povey, director of the UK National Autistic Society’s Centre for Autism, welcomed the findings. “This is a robust study which confirms what previous research has found: it is a myth that high mercury levels in pregnant mothers cause autism,” she said.
“Although the exact causes of autism are still not fully understood, research to date has shown it involves many complex and interacting factors, including genetics, the environment and the development of the brain.”
Povey encouraged additional research focussing on ways to help autistic people and their families to improve their quality of life, while Taylor suggested conducting additional research to determine “how the current guidelines have affected the consumption of fish in pregnant women overall.”