Pregnant women who drink six cups of coffee every day may have smaller babies than women who consume less caffeine, according to a Dutch study.
Researchers from the Erasmus Medical Center in Rotterdam followed more than 7,300 Dutch women from early pregnancy onward of whom between 2 and 3 percent said they consumed the caffeine equivalent of six cups of coffee per day during any trimester.
On average, their babies' length at birth was slightly shorter than that of newborns whose mothers had consumed less caffeine during pregnancy.
"Caffeine intake seems to affect length growth of the fetus from the first trimester onwards," researcher Rachel Bakker told Reuters Health.
Heavy caffeine consumers also had an increased risk of having a baby who was small for gestational age -- smaller than the norm for the baby's sex and the week of pregnancy during which he or she was born.
That finding, however, was based on a small number of babies, and the significance is uncertain. Of 104 infants born to women with the highest caffeine intakes, seven were small for gestational age.