No caffeine consumption safe in pregnancy, study finds
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No amount of caffeine consumption is safe during pregnancy, according to research published in the BMJ Evidence-Based Medicine.
“Chronic exposure to any chemical during pregnancy is cause for concern,” Jack E. James, PhD, professor of psychology at Reykjavik University in Iceland, told Healio Primary Care, adding that caffeine should not be an exception because it “happens to be widely consumed.”
Currently, James wrote, many guidelines for caffeine consumption in pregnant women call for reduced intake, despite an FDA recommendation in 1980 advising pregnant women to restrict or abstain from caffeine intake. The American College of Obstetricians and Gynecologists recommends that women limit their caffeine consumption to 200 mg, or about two cups of coffee, per day.
James conducted a narrative review of studies to assess current evidence on pregnancy outcomes related to caffeine intake and determine whether current recommendations on caffeine consumption in pregnancy are well-backed by studies. He searched PubMed, Google Scholar and other databases for studies published in the last 20 years.
The negative pregnancy outcomes identified by James included miscarriage, stillbirth, low birth weight, preterm birth, childhood acute leukemia, childhood overweight and childhood obesity.
After exclusions, 48 full-text articles were included in the study. Of those, 37 were original observational studies and 11 studies included 17 meta-analyses.
Among 42 sets of findings reported in the observational studies, James found that 32 showed significant caffeine-related risks, while 10 determined that there were either no or inconclusive associations between caffeine intake and these risks.
James reported that caffeine-related increased risks were at moderate to high levels of consistency with all pregnancy outcomes except preterm birth.
According to James, 14 meta-analyses unanimously found that maternal caffeine intake was associated with an increased risk for miscarriage, stillbirth, low birth weight and childhood acute leukemia. Three meta-analyses lacked reliable associations between maternal caffeine consumption in preterm birth. None of the meta-analyses identified elevated risks for childhood overweight or obesity,
Although the current study does not prove causation, James noted that many studies in the analysis identified dose-response associations between caffeine intake and pregnancy outcomes and that some studies did show a threshold of consumption at which these negative outcomes were not present, suggesting that causation is likely.
James said that the accumulated evidence consistently implicates that caffeine is not as harmless as it is often portrayed, and that the concept that there is a save level of caffeine consumption in pregnancy contrasts with scientific evidence.
James added that health authorities are “well-overdue” to change their position and recommend against caffeine during pregnancy.
In response to the findings, Christopher Zahn, MD, vice president of Practice Activities at ACOG, told Healio Primary Care that “our guidance remains that moderate caffeine consumption, less than 200 mg per day, does not appear to be a major contributing factor in miscarriage or preterm birth.”
He said that ACOG’s clinical guidance — which is based on a thorough review of current evidence — is reexamined every 18 to 24 months, and the ACOG Committee Opinion on moderate caffeine consumption in pregnancy was reaffirmed this year.
“While this study will likely be included in the next review, there is nothing that warrants immediate change to the current guidance,” Zahn said.
*Editor’s note: This story was updated on Aug. 27, 2020, to include comments from James and Zahn.