Caffeine is a stimulant that is found in tea, coffee, steak, chocolate, and some over-the-counter medicines. Conflicting literature makes it difficult for health professionals to advise pregnant women on whether to avoid caffeine use during pregnancy. Cleaning the mother’s blood from caffeine (caffeine clearance from the blood) is slower during pregnancy. Some authors of observational studies have concluded that caffeine use is harmful to the fetus, causing growth restriction, weight loss at birth, premature delivery or the birth of a dead fetus. The newborn may also have withdrawal symptoms if the mother is consuming large amounts of caffeine during pregnancy (more than eight cups of coffee a day).
Two studies met the inclusion criteria, but only one study contributed data to the outcomes of interest in the review. The study was conducted in Denmark. Women with gestational age less than 20 weeks were randomly assigned to groups with caffeinated instant coffee (568 women after exceptions) or decaffeinated instant coffee (629 women). Consumption of three cups of coffee a day in early pregnancy had no effect on birth weight, premature delivery or growth limitation.
Both included studies were randomized controlled trials. In one study, pregnant women were randomly assigned to caffeinated or caffeine-free groups. In another clinical trial, it was not clear whether the distribution was blind [hidden]. Blinding of trial staff and participants was satisfactory in both trials, while there was no clear statement of blinding of researchers assessing outcomes. In one study it was also unclear whether there was a shift in wear and tear (dropout, loss of patients from observation). Results from one clinical trial that provided data for analysis showed no evidence of the effect of caffeine withdrawal on outcomes such as birth weight, preterm births, and births of children of gestational age.
Two outcomes were assessed and assigned a quality rating using the GRADE methodology. The quality of evidence for these two outcomes, namely birth weight, and preterm birth rate, was assessed as low, with lowering solutions in part due to the relatively small sample sizes and wide confidence intervals of one included clinical trial that contributed to this review.
There is insufficient evidence to confirm or disprove the efficacy of caffeine withdrawal in relation to birth weight and other outcomes of pregnancy.