Is a Risk of Autism Related to Nutrition During Pregnancy?

Alison Jean Thomas
research word cloud

The question of whether risk of autism is related to nutrition during pregnancy is one that concerns all women hoping to conceive. With the rise in recorded numbers of ASD (autistic syndrome disorder) and a corresponding increase in autism awareness, research is turning to the role diet during pregnancy plays as an ASD risk factor. If you are planning to have a child or already pregnant, recent studies into three different areas of nutrition indicate you need to know how the food you eat could affect your baby's health.

Overeating as a Risk Factor

In recent years, the rise in autism has been correlated with that of obesity. Fearing a link between the two, a study of 2,734 children in the United States examined the combined effect of maternal pre-pregnancy obesity and maternal diabetes for ASD risk. Findings of the research, "The Association of Maternal Obesity and Diabetes With Autism and Other Developmental Disabilities," published in the January 2016 edition of Pediatrics were founded on physician diagnosis.

The Study

Researchers compared ASD risk among six groups defined by maternal pre-pregnancy obesity and diabetes status. Results showed maternal pregnancy obesity and pre-gestational diabetes (PGDM) were each associated with risk of ASD.

The significant risk was when obesity and diabetes coincided:

  • Mothers who began pregnancy with a pre-condition of diabetes and were also overweight were four times more likely to have an autistic child than those who had neither condition.
  • Obese mothers who developed gestational diabetes during pregnancy were three times as likely to have an ASD child.

A previous study carried out by the University of Utah, published in Pediatrics 2013, had concluded that ASD risk was linked to a slight but continuous weight increase in mothers. This signified that one of autism's gestational causes was weight gain.

Guidelines from The American Congress of Obstetricians and Gynecologists (ACOG) endorse:

  • Maximum weight gain of 35 pounds for women during pregnancy
  • Maximum weight gain of 25 pounds if the woman is overweight at the start of the pregnancy

For each five-pound increase above this level, risk of ASD rises. The reasons for this are not yet known. In an interview for Autism Speaks, Dr Paul Wang mentioned that it could be due to two factors, inflammation and oxidative stress when antioxidants fail to detoxify the harmful effects of free radicals. Both issues affect early brain development. Another theory is that excess fat may change women's hormone levels.

Parental Obesity Also a Risk Factor

feet standing on scale

Interestingly, a Norwegian study, "Parental Obesity and Risk of Autism Spectrum Disorder," carried out on 92, 909 children, examined links between maternal pre-pregnancy body mass index (BMI) and paternal BMI. The results, published in Pediatrics April 2014, showed that ASD risk was only slightly linked to the mother's weight (BMI ≥30). The link between paternal obesity and autistic disorder and Asperger was greater.

When appraising these studies, it is clear more research needs to be carried out to discover the relationship between ASD and parental obesity.

The sensible view is that of Anna Maria Wilms Floet, M.D., a behavioral developmental pediatrician at the Kennedy Krieger Institute's Center for Autism and Related Disorders in Baltimore. In Pregnancy she states, "Obesity rates and autism rates have both gone up over the past decades, yet that doesn't mean the two are connected." She recommends mothers watch their weight while pregnant to avoid complications due to blood pressure and diabetes.

Polyunsaturated Fats Help Prevent Autism

In the 2013 study, "Maternal Dietary Fat Intake in Association With Autism Spectrum Disorders" published by The American Journal of Epidemiology, researchers, set out to discover if ASD risk was related to periconceptional fat intake.

The Study

Study features included:

  • 317 mothers with an ASD child
  • 17,728 comparison mothers
  • Mothers were enlisted from the Nurses' Health Study II (index births in 1991-2007)
  • Researchers used a validated food frequency questionnaire for data collection

The theory was that ASD risk may be reduced through high intakes of omega-3 and other polyunsaturated fats, but low intakes would increase the risk.

The results revealed:

  • Increased intake of omega-6 fatty acids could reduce risk of ASD, but further study and replication is required.
  • Low intakes of omega-3 fatty acids and linoleic acid might increase risk.

This report ventures into a previously neglected area of research. It concluded that further investigation should consider the link between maternal intake of fats, neurodevelopment, and autism.

Using Fats

By using vegetable oils and eating a diet rich in nuts and seeds, you can increase your intake of polyunsaturated fatty acids. You don't want to consume more calories, so your total fats should remain the same.

  • Replace foods containing saturated fats, such as butter, lard, and cream, with vegetable oils.
  • Check the label to find out what kind of fats they contain.
  • Cut down on cheese and fatty cuts of beef and pork.

Periconceptional Folate Concerns

spoonful of pills

According to a case control study into maternal periconceptional folic acid intake and risk of ASD and developmental delay, published by American Journal of Clinical Nutrition, folic acid consumption before and throughout pregnancy may lower ASD risk. This confirms previous work connecting low folate intake to poor neurodevelopmental outcomes and ASD in children. Guidelines for folic acid supplements prior to and during pregnancy stand at 0.6 milligrams daily.

However, a subsequent study by Johns Hopkins Bloomberg School of Public Health presents a different picture.

The Study

Details of the study include:

  • 1,391 mother-child pairs took part.
  • Participants were from primarily a low-income, minority population of the Boston area.
  • Mothers joined from 1998 to 2013, at the time of their child's birth.
  • They were tracked for several years.
  • Within three days of delivery, researchers measured mothers' blood folate levels.
  • Ten percent of the women had too much folate.
  • Six percent had an excess amount of vitamin B12.

The Results

The study found the following:

  • Mothers with four times the adequate folate level following the birth doubled ASD risk.
  • Mothers with excessive vitamin B12 levels tripled ASD risk.
  • Combined extremely high vitamin B12 and folate increased risk of ASD 17.6 times.

In a news release by Johns Hopkins Bloomberg School of Public Health, M. Daniele Fallin, PhD, director of the Bloomberg School's Wendy Klag Center for Autism and Developmental Disabilities commented the official position on folate remains the same because "adequate supplementation is protective," but that too much may be harmful, so it is necessary to aim for optimal levels.

Folate In Your Diet

Ensure you know which foods contain folate. The question seems to be that of how much folate to consume and when. If you're worried about the amount of vitamin B12 and folate you're taking, either through supplements or diet, make a food diary in which you note all your supplements and daily food intake. Book an appointment to consult a physician about your concerns so he can reassure you or suggest changes. It is important you talk to your doctor about your folate intake.

Prepare for Pregnancy Through Wise Nutrition

In the past, women were encouraged to "eat for two" during pregnancy; however, now this is held to be detrimental to the health of both mother and child. Autism Research Institute recommends a woman should spend up to a year preparing for pregnancy. It endorses important dietary and lifestyle choices to ensure she is at her optimal fitness level when she conceives. Among these choices are organically grown vegetables, fruits, nuts, grains, and lean proteins.

Nutrition and ASD Risk Are Connected

Autism has multiple causes, all of which are still not known. Links are made between heredity, genetics, difficulties during pregnancy and delivery, medical problems, and environmental factors. However, through research, medical opinion is making connections between diet and autism prevention. These connections to autism risk should not be ignored.

Is a Risk of Autism Related to Nutrition During Pregnancy?