A pharmacist has slammed a recent study which concluded there is no safe level of caffeine consumption for pregnant women and would-be mothers, calling it “alarmist”
Professor Jack James, of Reykjavik University, Iceland, performed an analysis of observational studies which has been published in BMJ Evidence Based Medicine, reviewing current evidence on caffeine-related pregnancy outcomes.
Pregnant women have been advised that consuming a small amount of caffeine daily will not harm their baby. The UK NHS, the American College of Obstetricians and Gynecologists, the Dietary Guidelines for Americans and the European Food Safety Authority (EFSA) set this level at 200 mg caffeine, which approximates to roughly two cups of moderate-strength coffee per day.
However, Professor James concluded that current health recommendations concerning caffeine consumption during pregnancy are in need of “radical revision”.
Through database searches, Professor James identified 1,261 English language peer-reviewed articles linking caffeine and caffeinated beverages to pregnancy outcomes.
Of these he utilised 48 original observational studies and meta-analyses published in the past 20 years reporting results for one or more of six major negative pregnancy outcomes: miscarriage, stillbirth, low birth weight and/or small for gestational age, preterm birth, childhood acute leukaemia, and childhood overweight and obesity.
A total of 42 separate findings were reported in 37 observational studies; of these 32 found that caffeine significantly increased risk of adverse pregnancy outcomes and 10 found no or inconclusive associations. Caffeine-related risk was reported with moderate to high levels of consistency for all pregnancy outcomes except preterm birth.
Professor James found that eleven studies reported on the findings of 17 meta-analyses, and in 14 of these maternal caffeine consumption was associated with increased risk for four adverse outcomes: miscarriage, stillbirth, low birth weight and/or small for gestational age, and childhood acute leukaemia. The three remaining meta-analyses did not find an association between maternal caffeine consumption and preterm birth.
No meta-analyses looked at the association between maternal caffeine consumption and childhood overweight and obesity, but four of five observational studies reported significant associations.
The author noted that this is an observational study, so can’t establish causation, and pointed out that the results could be impacted by other confounding factors, such as recall of caffeine consumption, maternal cigarette smoking and most importantly pregnancy symptoms. Pregnancy symptoms such as nausea and vomiting in early pregnancy are predictive of a healthy pregnancy and women who experience them are likely to reduce their caffeine intake, he said.
He said that the dose-responsive nature of the associations between caffeine and adverse pregnancy outcomes, and the fact some studies found no threshold below which negative outcomes were absent, supports likely causation rather than mere association.
Professor James concluded that there is “substantial cumulative evidence” of an association between maternal caffeine consumption and diverse negative pregnancy outcomes, specifically miscarriage, stillbirth, low birth weight and/or small for gestational age, childhood acute leukaemia and childhood overweight and obesity, but not preterm birth.
He suggested a revision of guidelines: “the cumulative scientific evidence supports pregnant women and women contemplating pregnancy being advised to avoid caffeine,” he said.
Dr Luke Grzeskowiak, a pharmacist and NHMRC Early Career Research Fellow in the Robinson Research Institute at the University of Adelaide, said Professor James’ conclusion that all pregnant women and women contemplating pregnancy should avoid caffeine is “overly alarmist and inconsistent with the evidence”.
“This report actually provides no new evidence on the topic, instead providing just one individual’s different perspective on existing evidence,” he said.
“It is true that previous studies have not confirmed a safe limit of caffeine intake during pregnancy, but this is very different to concluding that all levels of caffeine intake are harmful.
“In fact, previous studies are relatively consistent in showing that small to moderate amounts of caffeine (< 200 – 300 mg day) are unlikely to harm the pregnancy. The main associations, and therefore concerns, with negative pregnancy outcomes relate to women consuming high amounts of caffeine each day.
“Therefore, the current recommendations are and remain that women should limit caffeine intake where possible to less than 200-300 mg daily, but this is out of an abundance of caution rather than high-quality evidence.
“There are so many dos and don’ts associated with pregnancy and the last thing we need is to cause unnecessary anxiety.
“At the end of the day, women should be reassured that caffeine can be consumed in moderation during pregnancy.”