A team of research psychiatrists at the University of Utah recently published the findings of a study comparing a woman’s weight before and during pregnancy with the risk of her child being diagnosed with autism spectrum disorder (ASD). Their findings suggest a link between pregnancy weight and autism but no cause-and-effect evidence.

Dr. Deborah A. Bilder, an associate professor of psychiatry at the University of Utah, led the study. Her team analyzed vital records from 2009 and 2010 that involved more than 10,000 Utah children in two different study groups.

Excessive maternal body mass index (BMI) has been linked to pregnancy risks that include premature delivery and stillbirth as well as risk of childhood obesity and congenital abnormalities in the children of women with maternal BMI at 30 or higher. According to the medical records used in the study, 51 percent of all women pregnant in Utah during the study period were said to carry excessive weight during pregnancy. One in three of them was clinically overweight during pregnancy.

In one group Bilder’s team studied, maternal weight comparisons were made between 128 autistic 8-year-old children in the Salt Lake Valley with 10,920 children of the same age and living in the same area.

A second study group involved 288 children diagnosed with ASD. The weight of the mothers during pregnancy with each autistic child was compared with her weight during pregnancies with siblings not affected by ASD.

Research findings indicate a link between a mother’s excessive weight before and during pregnancy and the chance the child she bears is at higher risk for autism. Autism in Utah is estimated to affect 1 in 63 children. The US Centers for Disease Control and Prevention (CDC) estimates a higher nationwide incidence of the disorder: as many as 1 in 47 children.

Bilder cautions her research alone is not reason to change diets during pregnancy but considers it “one more piece of the autism puzzle” that suggests the need for further investigation. She adds, “these findings suggest that weight gain during pregnancy is not the cause of ASD but rather may reflect an underlying process that it shares with autism spectrum disorders, such as abnormal hormone levels or inflammation. ”

Source: Utah Department of Health/PRAMS Perspectives. Gestational Weight Gain in Utah: Populations and Interventions. January 2013. PDF file.