New research suggests that drinking caffeinated drinks during pregnancy raises the risk of having a low birth weight baby.
Caffeine has long been linked to adverse effects in pregnant women, prompting many expectant mothers to give up coffee and tea. But for those who cannot do without their morning coffee, health officials over the years have offered conflicting guidelines on safe amounts during pregnancy.
The World Health Organization recommends a limit of 300 milligrams of caffeine a day, equivalent to about three eight-ounce cups of regular brewed coffee. The American College of Obstetricians and Gynecologists stated in 2010 that pregnant women could consume up to 200 milligrams a day without increasing their risk of miscarriage or preterm birth.
In the latest study, published in the journal BMC Medicine, researchers collected data on almost 60,000 pregnancies over a 10-year period. After excluding women with potentially problematic medical conditions, they found no link between caffeine consumption – from food or drinks – and the risk of preterm birth. But there was an association with low birth weight.
For a child expected to weigh about eight pounds at birth, the child lost between three-quarters of an ounce to an ounce in birth weight for each 100 milligrams of average daily caffeine intake from all sources by the mother. Even after the researchers excluded from their analysis smokers, a group that is at higher risk for complications and also includes many coffee drinkers, the link remained.
One study author, Dr. Verena Sengpiel of the Sahlgrenska University Hospital in Sweden, said the findings were not definitive because the study was observational, and correlation does not equal causation. But they do suggest that women might put their caffeine consumption “on pause” while pregnant, she said, or at least stay below two cups of coffee per day.
This post has been revised to reflect the following correction:
Correction: February 20, 2013
An earlier version of this article described incorrectly the relationship between the amount of caffeine a pregnant woman drank and birth weight. For a child expected to weigh about eight pounds at birth, the child lost between three-quarters of an ounce to an ounce in birth weight for each 100 milligrams of average daily caffeine intake by the mother, not for each day that she consumed 100 milligrams of caffeine.