High maternal plasma folate, excess vitamin B12 linked to increased ASD risk in child

Maternal plasma folate levels of more than 59 nmol/L, far exceeding the cutoff suggested by the WHO, and vitamin B12 in excess of 600 pmol/L, were associated with an elevated risk for autism spectrum disorder in the child, according to researchers from the Johns Hopkins Bloomberg School of Public Health.

The researchers, who will present their findings on May 13 at the 2016 International Meeting for Autism Research in Baltimore, further concluded that the risk for autism spectrum disorder (ASD) was highest in children with mothers who had excess levels of both folate and vitamin B12.

“This research suggests that this could be the case of too much of a good thing,” Ramkripa Raghavan, MPH, MSc, a DrPH candidate at the Bloomberg School and lead author of the study, said in a press release. “We tell women to be sure to get folate early in pregnancy. What we need to figure out now is whether there should be additional recommendations about just what an optimal dose is throughout pregnancy.”

To determine the relationship between maternal multivitamin supplementation during pregnancy, and plasma biomarkers for folate and vitamin B12 at 24 to 72 hours after delivery, and the later risk for ASD in children, the researchers drew data from the Boston Birth Cohort, part of a longitudinal, prospective study recruiting low-income, urban, primarily minority mother-child pairs. The 1,391 pairs were selected at Boston Medical Center and followed via electronic medical records from birth through childhood between 1998 and 2013.

There were 107 children who were diagnosed with autism, Asperger syndrome and/or pervasive developmental disorder not otherwise specified, and categorized as having ASD. The 1,284 children who were not diagnosed were categorized as “typical.” The researchers used Cox proportional hazard regression to account for differential follow-up time, and pertinent covariates were adjusted.

According to the researchers, maternal multivitamin supplements taken three to five times per week were associated with significantly lower risk for ASD in children across all trimesters (HR = 0.33, 0.38 and 0.43 for the first, second and third trimesters respectively). However, vitamin B12 levels of more than 600 pmol/L were associated with significantly increased risk for ASD (HR = 3.01; 95% CI, 1.64-5.52; P = .001). Folate levels of more than 59 nmol/L were also associated with an increased risk for ASD (HR = 2.27; 95% CI, 1.26-4.09; P = .007). High levels of both folate and vitamin B12 produced the highest risk for ASD (HR = 17.59; P < .001). – by Jason Laday

Disclosure: Healio Family Medicine could not confirm the researchers’ relevant financial disclosures.

Reference:

Raghavan R, et al. Maternal plasma folate, vitamin B12 levels and multivitamin supplement during pregnancy and risk of autism spectrum disorders in the Boston Birth Cohort. Presented at the International Meeting for Autism Research, May 11, 2016; Baltimore.