FRIDAY, Jan. 26, 2007 (HealthDay News) -- Women who consume moderate amounts of caffeine during pregnancy do not have a greater risk of premature births or underweight babies, new research shows.
This study, published in the Jan. 27 issue of the British Medical Journal, joins a host of other studies that have yielded results both pro and con on the issue.
But, according to the authors, this trial is more definitive.
"This study is better than the other studies that have been published because it's based on a much stronger design," said senior author Dr. Jorn Olsen, professor and chair of the department of epidemiology at the University of California, Los Angeles. "This study provides pretty good evidence that caffeine, in itself, does not reduce fetal growth, although it may have other side effects."
But expectant mothers shouldn't go running off to Starbuck's just yet.
"This study seems to refute that high caffeine intake can lead to low birth weight and perhaps preterm delivery, but it's only one study," said Dr. Jennifer Wu, an obstetrician/gynecologist at Lenox Hill Hospital in New York City. "I still think you probably want to decrease consumption of stimulants during pregnancy and have as healthy a lifestyle as possible."
In addition to low birth weight and preterm delivery, some studies have shown that drinking a lot of coffee during pregnancy increases the risk that a baby will be stillborn or die in the first year of life. These women may also be more likely to suffer a miscarriage.
For this study, Olsen and his colleagues monitored 1,207 healthy women who drank at least three cups of coffee a day and who were less than 20 weeks pregnant. Participants were divided into two groups, one receiving caffeinated instant coffee and the other receiving decaffeinated instant coffee.
Participants were also asked about other potential sources of caffeine (for example, tea and cola).
No significant differences were found for length of pregnancy or birth weight between the two groups. Among women drinking caffeinated coffee, 4.2 percent of infants were born prematurely, and 4.5 percent were small for gestational age, vs. 5.2 percent premature births and 4.7 percent underweight in the decaffeinated group.
Women who smoked more than 10 cigarettes a day had babies with a lower mean birth weight if they were randomized to the caffeinated group compared with smokers randomized to the decaffeinated group. Although that finding may be due to chance, the authors stated, it could also be because smokers metabolize caffeine faster than non-smokers.
And caffeine may have effects beyond the ones studied.
"We cannot rule out that caffeine could produce miscarriage or other things. Our study only looked at fetal growth and preterm delivery, so that's the only thing we know about," Olsen said. "We have no reason to believe that coffee is a necessary food item for pregnant women. I think it's wise that they should be a little cautious, but, in any case, if a pregnant woman gave birth to a low birth weight baby, it's highly unlikely that this was the case."
Get more advice on caffeine and pregnancy from the March of Dimes.