Current research by the Center for Disease Control and Prevention estimates that autism spectrum disorder (ASD) affects about 1 in 68 children in the United States. While the exact causes for ASD are not yet known, previous and now widely discredited scientific research contributed to the popular belief that vaccinations can cause the disorder. Despite new research that increasingly disproves any potential link, this belief continues to linger. To further investigate a possible connection, a recent study published in JAMA Pediatrics examined the association between maternal influenza vaccination during pregnancy and an increased risk of ASD for children.
For this cohort study, researchers from Kaiser Permanente Northern California examined the mothers of 196,929 children born at Kaiser Permanente between Jan. 1, 2000 and Dec. 31, 2010. Influenza was diagnosed in 0.7 percent of the women with a gestational age of at least 24 weeks, and 23 percent of these women received an influenza vaccination during the remainder of their pregnancy. After adjusting for covariates, the team found there to be no substantial link between a mother’s vaccination for influenza during her pregnancy and the subsequent development of autism in her child.
Overall, only 1.6 percent of children in the study were diagnosed with ASD. However, in a trimester-specific analysis, there was a slight correlation between first trimester influenza vaccination and an increased risk of ASD for children. While the researchers ultimately determined that this correlation could be due to chance, the possible increased risk in the first trimester suggests additional research is needed.
Based on their findings, the research team has not called for any changes to influenza vaccine policy or practice for pregnant women. Their research supports current medical recommendations that all women receive the influenza vaccine when pregnant, as the weakened state of a pregnant woman’s immune system increases a child’s susceptibility to short- and long-term risks such as premature birth, low birth weight and illness in early life. Further, studies show that maternal infections that occur and are not treated during pregnancy can increase the risk of ASD for children.