Childhood ADHD & Autism Linked To Pre-pregnancy Obesity

Women overweight or obese prior to getting pregnant were more likely to have a child who is autistic or with behavioural problems, according to a new review by a team of researchers from Duke University Medical Center and Virginia Commonwealth University.

The review pooled the results of 32 studies, looking for a possible link between whether a woman was overweight or obese before she became pregnant, and neurodevelopmental disorders like attention deficit hyperactivity disorder (ADHD) and autism spectrum disorders (ASD) in their children.

The causes of these conditions, aside from possible genetic factors, currently are not well understood.

Increased Risk

The study found that overall, mothers who were overweight before they became pregnant had about a one-third increased risk of having a child with ADHD, and a 10% increased risk of having a child with autism spectrum disorders, compared with normal-weight women. If the mothers were obese, the risks were slightly higher (two-thirds and one-third increased risk).

Although this is a useful review, it does have limitations. The findings are based on observational studies that varied widely in their studied populations, how they assessed weight status and neurodevelopmental outcomes, and the other factors taken into account.

It’s possible that genetics, health, lifestyle and other family environmental factors could have played a role in the likelihood of having a child with one of these conditions.

Therefore, the studies aren’t able to prove there’s a direct link between these disorders and women who were overweight or obese before falling pregnant. But the various risks of being overweight or obese are well established.

Mother’s Weight And Child Behavioural Conditions

The researchers carried out a systematic review followed by a meta-analysis.

They looked at existing evidence to investigate the association between mothers being obese or overweight before they were pregnant, and neurodevelopmental conditions such as ADHD or autism spectrum disorders in their children.

The prevalence of child behavioural and developmental conditions in western countries is rising, but the causes are poorly understood.

Antenatal exposure to environmental toxins and maternal stress and nutrition have been suggested as possible causes in previous research. This study looked at the possible link with a mother’s weight.

Systematic reviews are the best way of gathering the published literature on a topic to look for a potential association between an exposure and an outcome. The difficulty is that the findings of a systematic review are only as good as the studies the researchers include as part of their analysis.

As the studies included in this research are observational, it’s difficult to account for many other factors that could have had an influence on the findings.

Basic Results

Pooling data from 22 cohort studies looking at being overweight, mothers who were overweight before becoming pregnant were more likely to have a child with one of the conditions being investigated (odds ratio [OR] 1.17, 95% confidence interval [CI]: 1.11 to 1.24).

From 25 cohorts that included obese women, obesity before pregnancy was associated with an even greater increase in risk of having a child with one of the conditions (OR 1.51, 95% CI: 1.35 to 1.69).

More specifically, mothers who were overweight before pregnancy were more likely than normal-weight mothers to have a child with:

  • ADHD (OR 1.30, 95% CI: 1.10 to 1.54)
  • autism spectrum disorders (OR 1.10, 95% CI: 1.01 to 1.21)
  • cognitive or intellectual developmental delays (OR 1.19, 95% CI: 1.09 to 1.29)

There was no link between a mother being overweight and having a child with emotional or other behavioural problems. Mothers who were obese before pregnancy were even more likely to have a child with these conditions:

  • ADHD (OR 1.62, 95% CI: 1.23 to 2.14)
  • autism spectrum disorders (OR 1.36, 95% CI: 1.08 to 1.70)
  • cognitive or intellectual delay (OR 1.58, 95% CI: 1.39 to 1.79)
  • emotional or behavioural problems (OR 1.42, 95% CI: 1.26 to 1.59)

Conclusions

The researchers concluded that:

“Results show that children born to mothers who are overweight or obese are at a higher risk of neurodevelopmental problems, including ADHD, ASD, greater emotional and behavioural problems, and cognitive delay.”

They say that a critical next step could be to start looking at biological causes for the links, such as maternal obesity possibly influencing inflammation levels during a child’s development in the womb.

The causes of conditions such as ADHD and autism spectrum disorders remain largely unknown. But we do know that being overweight or obese has adverse health effects.

If you’re planning to have a baby, taking steps to lose weight (if you’re overweight) before conceiving could benefit both you and your baby, as well as reduce the risk of complications during pregnancy.

The work was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Sanchez, C. E., Barry, C., Sabhlok, A., Russell, K., Majors, A., Kollins, S. H., and Fuemmeler, B. F. (2017)
Maternal pre-pregnancy obesity and child neurodevelopmental outcomes: a meta-analysis
Obesity Reviews, doi: 10.1111/obr.12643

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