Pregnant women may find the nine months they’re carrying a baby difficult, but when it comes to how to be pregnant, there are only a few major rules to live by: eat right, exercise, and avoid caffeine, drugs, and alcohol. Yet, one in 13 American pregnant women admitted to drinking alcohol in the latest Centers for Disease Control and Prevention (CDC) study. The effects of this early alcohol exposure are the subject of a new study, which found that children born to these mothers grew up with developmental brain deficits.

Fetal alcohol spectrum disorders (FASD) are a group of conditions that arise after a child has been exposed to alcohol in the womb. To put it simply, when a pregnant mom drinks alcohol, so does her child — a result of the alcohol passing from the mom’s blood through the umbilical cord. Too much alcohol, and the baby can be born with any one of the FASD conditions: fetal alcohol syndrome, alcohol-related neurodevelopmental disorder, or alcohol-related birth defects. Each one of these causes the baby to be born with abnormal facial features, small head sizes, growth problems, and problems in the central nervous system and the brain.

The researchers of the current study were interested in seeing how FASD affected the development of brain function in 7- to 14-year-old kids over an extended period of time. “Functional magnetic resonance imaging (fMRI) has been used to observe brain activity during mental tasks in children with FASD, but we are the first to utilize these techniques to look at brain activation over time,” study author Dr. Prapti Gautam said in a press release. “We wanted to see if the differences in brain activation between children with FASD and their healthy peers were static, or if they changed as children got older.”

Most normally developing children experience a boost in cognitive function, particularly working memory and attention, as they go from elementary school to middle school. In order for this to occur, they first need to undergo improvements in visuospatial attention, or the way our brain focuses on things and processes them further. But the researchers found that the brains of children with FASD couldn’t activate as fast as healthy children.

For the study, the researchers enlisted 31 kids with FASD and 30 without it to undergo an overall total of 122 fMRI scans over the course of two years. While they underwent the scans, they also completed tasks meant to activate parts of their brains responsible for visuospatial attention, among other things. Although their performance on the tasks was comparable, the researchers found that there were “significant differences in development brain activation over time between the two groups,” said Dr. Elizabeth Sowell, director of the Institute’s Developmental Cognitive Neuroimaging Laboratory, in the release. “While the healthy control group showed an increase in signal intensity over time, the children with FASD showed a decrease in brain activation during visuospatial attention, especially in the frontal, temporal, and parietal regions.”

It’s these problems, among so many others that children with FASD develop, that have caused some people to mistake FASD for attention deficit hyperactivity disorder (ADHD). According to a study from April, this happens because so many teachers look for signs of ADHD, but rarely FASD. Unfortunately, the best way to treat kids with FASD — there is no cure — is to catch it with early intervention, which can improve their development.

Not every woman who drinks while pregnant will give birth to a child with FASD (But why take a chance?), and there are no exact figures on how many children are born with FASD. The CDC estimates that as many as two children per 1,000 are born with fetal alcohol syndrome, and about three times that many have FASD.

Source: Gautam P, Nunez SC, Sowell ER, et al. Developmental Trajectories for Visuo-Spatial Attention are Altered by Prenatal Alcohol Exposure: A Longitudinal FMRI Study. Cerebral Cortex. 2014.