Study indicates potential link between influenza during pregnancy and autism
Although researchers found no evidence that maternal influenza alone was associated with autism spectrum disorder among children, they did observe a nonsignificant trend indicating an increased risk for autism among children whose mothers had laboratory-confirmed influenza and self-reported symptoms of influenza-like illness during pregnancy.
Their study, published in mSphere, is the first of its kind to assess whether laboratory-confirmed influenza during pregnancy is associated with an increased risk for autism spectrum disorder (ASD), according to a press release.
“Although chance may explain our findings, the magnitude of the potential association may be of biological importance, and dismissing our findings could result in failure to detect a bona fide association (type II error),” Milada Mahic, PhD, of the Center for Infection and Immunity (CII) at Columbia University’s Mailman School of Public Health and the Norwegian Institute of Public Health, and colleagues wrote.
The researchers examined data on 338 mothers of children with ASD and 348 mothers of children without an ASD diagnosis enrolled in the Autism Birth Cohort Study. The analysis included self-reported questionnaires regarding influenza symptoms and blood samples obtained at mid-pregnancy and after delivery.
The overall incidence of maternal influenza was 45%, with 35% of cases and 34% of controls having influenza A and 21% of cases and 27% of controls having influenza B. Nineteen percent of cases and 14% of controls reported symptoms of influenza-like illness.
According to the researchers, there was no association between a confirmed influenza diagnosis during pregnancy and risk for ASD in children. However, the odds of having a child with an ASD diagnosis were nearly twice as high among seropositive women who reported influenza-like symptoms during pregnancy than among seronegative women without symptoms (adjusted OR = 1.93; 95% CI, 0.95-3.89), but the association was not statistically significant, especially after adjusting for other testing, the researchers noted.
“Symptoms are important because they may indicate the extent to which the mother’s immune system is fighting the flu,” Mahic said in a press release. “If infection is contributing to increased risk, it likely comes from inflammation related to maternal immune system response rather than the flu infection itself. Further research is warranted.”
According to the release, the findings add to existing research that showed mothers hospitalized for a viral infection in the first trimester and those with a bacterial infection during the second trimester had an increased risk for having a child with ASD. Other findings from the Autism Birth Cohort Study indicated that the odds for an ASD diagnosis were nearly twice as high among children born to women actively infected with genital herpes during early pregnancy. In addition, another recent study suggested that maternal fever during pregnancy also may increase the risk for ASD.
“The fetal brain undergoes rapid changes that make it vulnerable to a robust maternal immune response,” W. Ian Lipkin, MD, director of CII and John Snow Professor of Epidemiology at the Mailman School, said in the release. “That said, mothers should not conclude that having an infection during pregnancy means that their child will develop autism. It may simply be one among many risk factors.” – by Stephanie Viguers
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