Mark A. Klebanoff and Sara A. Keim, of The Research Institute at Nationwide Children's Hospital in Ohio, found although caffeine is commonly consumed during pregnancy, few studies have explored the link between "in utero caffeine exposure and offspring cognition or behavior during childhood." The American College of Obstetricians and Gynecologists finds expectant mothers concerns stem from the fact caffeine can cross the placenta and increase maternal catecholamine levels. The latter are one of the biomarkers for stress, and maternal stress is believed to be a trigger for preterm birth.
Researchers' analyzed data collected from 2,197 expectant mothers (later on their children) who were participants in the Collaborative Perinatal Project (CPP) from 1959 to 1974; this period was reportedly one where few people worried about the effects of caffeine. Researchers were particularly interested in a chemical called paraxanthine, a central nervous stimulant. By analyzing this caffeine marker, researchers could "investigate a broader range of caffeine intake than if a similar study was done today."
After comparing paraxanthine levels at 20 and 26 weeks gestation to the child's intelligence quotient (IQ) and behavioral problems at ages 4 and 7, researchers found, or rather did not find consistent patterns between maternal caffeine ingestion and children's IQ and behavior at the studied points in their lives. However, of the children involved in the CPP, about 11 percent were considered obese at age 4 and about 7 percent at age 7. That said, researchers did not find an association between caffeine intake and future incidence of childhood obesity.
"Taken as a whole, we consider our results to be reassuring for pregnant women who consume moderate amounts of caffeine or the equivalent to 1 or 2 cups of coffee per day," Keim, who is also a faculty member at The Ohio State University College of Medicine, said in a press release.
Live Science cited findings of the few other studies that have already deemed it safe for expectant moms to enjoy their morning cup (or cups) of coffee: One study conducted in 2012 found in utero caffeine exposure didn't necessarily mean babies woke up more at night. And according to ACOG, moderate caffeine consumption is thought to be safe.
Source: Klebanoff MA, Keim SA. Maternal Caffeine Intake During Pregnancy and Child Cognition and Behavior at 4 and 7 Years of Age. American Journal of Epidemiology. 2015.