By the time I sat down with my doctor after learning I was pregnant for the first time, my excitement had been replaced with a monster-sized worry that I had already harmed the baby growing inside me.
I took a deep breath and confessed I had been on a wine tour in Napa Valley for the beginning of the pregnancy. Unaware I had conceived, I drank in my first trip to the region—literally and with gusto.
“That’s not a big deal,” my doctor said, waving her hand. She dropped the lighthearted tone for the next question, though. “You are taking folic acid, right?” Most days, I was. For years the importance of taking a daily prenatal vitamin has been drilled into women just thinking of becoming pregnant; when we decided to try for a baby, I too had obliged. The rationale for this is that folate, also called folic acid, has long been linked with proper spine formation in fetuses; pregnant women who don’t have enough folate risk having a baby with spina bifida (a debilitating condition in which baby is born with its spinal column splayed) or other neural tube defects.
To chase away that worry, many of us dutifully swallow prenatal vitamins day in and day out, despite nausea, headaches and the long list of extra must-do’s (and don'ts) that pregnancy adds. For a moment last week, new research nearly—dangerously—turned that habit on its head. Presented at an autism conference for scientists, the study generated panic-inducing headlines warning that expectant moms who are taking folic acid supplements might actually be doing harm to their unborn infants by putting them at risk for autism.
The coverage ignited questions over whether prenatal vitamins ought to be abandoned altogether, branded unsafe. But the opposite is true, say the study’s authors.
“A mom on the street should not be worried about this—she should not stop taking folic acid supplements,” said Dani Fallin, one of the lead researchers involved in the study and chair of the Department of Mental Health at Johns Hopkins University in Baltimore. “Using vitamin supplementation, particularly during very early pregnancy, appears to be protective for autism—women who supplement have a lower risk of autism in their child,” Fallin said.
She and her colleagues followed 1,391 mothers in Baltimore between 1998 and 2013; all had their blood tested for levels of folate and vitamin B12, also commonly found in prenatal supplements and used to help nausea, within days of giving birth. While women who used adequate amounts of folate had babies with a low risk of developing autism, those who were folate-deficient (meaning levels were extremely low) were at a higher risk for autism.
“You definitely don’t want to be too low in folate. But there may be a concern if you're way too high,” Fallin said. Indeed, a small subset of women (about 10 percent) showed excessively high levels of folate and vitamin B12 in their blood post-birth—about four times what is considered an adequate amount. Their children all had a higher risk of being diagnosed with autism.
Fallin was cautious to point out that her team has not identified the cause of the excessive vitamin levels. Possible explanations include supplements, fortified foods (folate and B12 are added to many processed foods, including bread and cereals) and genetic differences that may prevent some people from breaking down or absorbing the vitamins.
By putting out their preliminary findings to the group of scientists who attended the International Meeting for Autism Research—meaning they have not been peer-reviewed, nor published in a journal—Fallin’s team hopes to inspire other researchers to look at the same issues. More investigation needs to be done to unearth the cause of the high folate and B12 levels; her team’s findings must be replicated to take on legitimacy, Fallin said.
“In the world of autism, advocates and families are clamouring to know what’s happening on the cutting edge of science. The challenge is to create an awareness that this is not settled science," she said. “Way down the road, it may be that we need to think about how to better monitor these kinds of [vitamin] levels during pregnancy so that obstetricians can work with their patients to make sure they don’t get to high or too low,” Fallin said, adding: “We will not be changing any recommendations any time soon.”
So, keep popping those vitamin pills, ladies. You’re still on the hook.