Vitamins in first month of pregnancy protect against autism
Vitamins intake during the first month of pregnancy may protect against autism spectrum disorder (ASD) recurrence in younger siblings of children with ASD, according to a new study.
“This study is the first to our knowledge to suggest that maternal prenatal vitamin intake during the first month of pregnancy may reduce ASD recurrence by half in younger siblings of children with ASD in high-risk families,” said researchers. This may have important clinical and public health implications if verified in future studies.
The study included 241 younger siblings (mean age 36.5±1.6 months; 58.1 percent male), of whom 52.3 percent (n=126) were determined to have typical development (TD). Fifty-five (22.8 percent) fulfilled the algorithmic criteria for ASD while 60 (24.9 percent) were non-TD. [JAMA Psychiatry 2019;doi10.1001/jamapsychiatry.2018.3901]
While almost all mothers (95.6 percent) took prenatal vitamins at some point during pregnancy, most (63.9 percent; n=154) did not follow the recommended initiation period of 6 months prior to pregnancy and only 128 took the vitamins in the first month of pregnancy. Giving birth to a second child with ASD was less frequent in these mothers (14.1 percent vs 32.7 percent).
After statistical adjustment for confounders, multivariable multinomial logistic regression analysis revealed that children born to mothers who took prenatal vitamins in the first month of pregnancy were significantly less likely to be diagnosed with ASD (adjusted relative risk [RR], 0.50; 95 percent CI, 0.30–0.81).
Similarly, autism severity, as measured by the Autism Diagnostic Observation Schedule, was lower in infants born to mothers who were on prenatal vitamins during the first month of pregnancy (adjusted estimated difference, –0.60; –0.97 to –0.23). In contrast, prenatal vitamin intake did not appear to have a significant benefit for reducing non-TD risk (RR, 1.14; 0.75–1.75).
Moreover, folic acid supplements appeared to have the strongest effect. Mothers who were in the highest tertile of total mean intake during the first month of pregnancy were less likely to give birth to a child that would be diagnosed with ASD (adjusted RR, 0.42; 0.17–0.99; p=0.048), though no effects were observed for non-TD likelihood (adjusted RR, 1.34; 0.72–2.49; p=0.36).
The threshold value for folic acid was 600 µg (adjusted RR, 0.51; 0.31–0.82), at or above which the likelihood of being diagnosed with ASD was reduced.
The same was true for iron intake, which also significantly reduced the risk of an ASD diagnosis for those in the top two tertiles of total mean daily intake during the first month of pregnancy (middle tertile: adjusted RR, 0.57; 0.33–0.98; top tertile: adjusted RR, 0.52; 0.30–0.92).
“Considering the potential for greater genetic susceptibility in these families, these findings, if replicated, imply that susceptibility could potentially be overcome by environmental manipulation,” said researchers.
“Future work should examine the contributions of specific nutrients from supplements as well as food sources, overall diet quality and biologic measurements of nutrient status, as well as investigate dose thresholds, interactions with genetic variants and potential mechanisms,” they added.