No amount of alcohol a pregnant woman drinks is safe for a developing baby, according to the Centers for Disease Control and Prevention.
Now new research finds that maternal alcohol consumption may not just impact the baby a woman is carrying, but also that baby's future children and even grandchildren.
Alcohol can spark epigenetic changes that persist across generations, according to the study from the University of California Riverside, published in the journal Cerebral Cortex.
CDC Vital Signs, February 2016. American Journal of Preventive Medicine, November 2015 | Aaron Thorup, CDC Vital Signs, February 2016. American Journal of Preventive Medicine, November 2015
"We have evidence today that the effects of prenatal alcohol exposure could pass through to other generations, negatively impacting offspring who didn't have direct alcohol exposure," said Kelly Huffman, psychology professor at UC Riverside, who led the research.
The CDC reports that three-fourths of women actively wanting to get pregnant say they drink alcohol. More than 3 million American women are at risk of exposing a developing baby to alcohol, due in part to a lag time very early in the pregnancy before a woman knows that she's pregnant. That may create a window where even women who would never drink if they knew they were pregnant place their developing baby at risk. And some pregnant women mistakenly believe it's possible to drink moderately without risk to the babies they are carrying.
"No amount of alcohol in any trimester is considered safe," said Julia Robertson, the Utah Department of Health's Pregnancy Risk Line's Mother to Baby program manager.
Alcohol + babies = problems
Babies born to women who drink during pregnancy may suffer fetal alcohol spectrum disorder (FASD), which the CDC describes as "physical, behavioral and intellectual disabilities that last a lifetime." Fetal exposure to alcohol can create issues from behavioral problems to developmental disabilities, problems with key organs like the heart and kidneys, low birth weight, learning disabilities and reasoning challenges. It has been linked to poor mental health, substance abuse and even criminal involvement, among other things.
Babies exposed to alcohol prenatally can grow up with significant lifelong challenges, Robertson said. They may make bad decisions, struggle in school and find it difficult to keep both friends and jobs. Their families are also impacted. If those babies grow up to have children of their own, they may not have picked up the skills they need to be good parents.
Many physical problems are also associated with fetal alcohol exposure.
"We know alcohol increases the chance for birth defects. We see heart defects. We see facial changes. And we see, most importantly, effects to the child's brain. These effects to the brain are with that child for their lifetime. Alcohol is a bad actor," she said.
While no amount of alcohol is considered safe, Robertson said the risk line tries to reassure women who find they've been using mouthwash that contains alcohol, or who had a glass of wine a couple of times before learning they were pregnant.
"With alcohol, we want to know the amount and when so we can give a proper risk assessment to the woman contacting us," Robertson said. "But if you are sexually active, not using birth control and are binge drinking, we'd definitely like to talk about that with you."
"People have known about fetal alcohol syndrome for a long time, but it was always discussed as 'if a mother drinks a lot of alcohol when she's pregnant, her baby is affected," Huffman said. But it was considered a one-generation issue that would not impact future generations — "a one and done. We are now finding out that's incorrect."
Huffman's lab at the UC Riverside previously showed that prenatal ethanol exposure (PrEE) changes the anatomy of the neocortex, which is the part of the brain that's responsible for the complex behavior and cognition that are hallmarks of being a human.
Using mice, they showed that alcohol exposure disrupted the wiring in that part of the brain, messing up connections and altering gene expression.
Subsequently, using imaging, the findings were replicated in humans. The prenatal alcohol exposure disrupted how brain connections were organized through a mechanism known as epigenetic change, said Huffman.
She said that because DNA isn't altered by experience, it was believed that the effects of one's experiences would not be passed on to subsequent generations. But experiences and exposures can make epigenetic changes to chromosomes that affect how genes are expressed, and it's becoming clear those can be passed to offspring across generations, Huffman said.
Epigenetic changes may occur with age, or they may be due to environmental factors like toxins or lifestyle factors like alcohol consumption or disease. While those factors don't change DNA coding, they can change its details, disrupting gene expression, perhaps making it happen at the wrong point in development, for example. And those differences can be passed on to the next generation.
Huffman and her colleagues used a transgenerational mouse model with male mice offspring. The first generation was directly exposed to alcohol during development. The second generation had indirect exposure through the sperm that came from the germ cells in the first-generation mice who had been exposed.
The third-generation mice had not been exposed, either directly or through germ cells. "But when we did tests and looked at the modifications, they were still happening. We could demonstrate a heritable condition that can be passed on," Huffman said.
Prenatal exposure changes motor behavior and increases anxiety in offspring, among other things. The new findings show that negative changes can pass to future generations that were not even directly exposed to ethanol. Using mouse models, they showed that second and third generations had similar effects to those with direct exposure.
"We found that body weight and brain size were significantly reduced in all generations of PrEE animals when compared to controls; all generations of PrEE mice showed increased anxiety-like, depressive-like behaviors and sensory-motor deficits," Huffman said in background material accompanying the study.
The strong transgenerational effects indicate fetal alcohol spectrum disorders may be heritable in humans.
Early epigenetic research looked at starvation and followed the impact of a short but extremely severe famine on pregnant women. Those women had severe nutritional deficiency during pregnancy, Huffman said. And though their children and grandchildren and great-grandchildren had not suffered in the famine, they still showed markers of nutritional deficits.
"I hope people understand the danger," she said. "When you have a child, it's pretty much your whole life. You have to give up some things, make sacrifices. It's really not that big a deal to do that — to stop drinking for nine months. Just go without."