Even a little bit espresso whereas pregnant can have an effect on the burden of the new child

“This birth weight reduction is within the range we see in birth weight reductions in women who smoke while pregnant,” Gleason said, noting that smokers tend to give birth to babies an average of 1.8 to 7 ounces lighter than that Non-smoker.

The results were published online on March 25th in the JAMA Network Open.

But while these results are worrying, pregnant women shouldn’t rush to throw away all of their coffee beans, tea bags, and diet colas, said Dr. Jill Berkin, an assistant professor of maternal-fetal medicine at Mount Sinai Health System in New York City.

The results of this study contradict previous research that found no significant association between caffeine and fetal growth, Berkin said.

Additionally, the effects of caffeine on birth size and weight observed here weren’t enormous, Berkin said, and so it’s hard to say whether these babies would suffer from the long-term health effects typically associated with stunted development of the fetus.

These effects can include an increased risk of obesity, heart disease and diabetes later in life, the researchers said in the Supporting Information.

“It was so small that there was only a 3 ounce difference in body weight. Whether the 3 ounces will have any long-term clinical effects on a baby remains to be determined,” said Berkin. “We know that there are worse outcomes in babies who have less than the 10th percentile of expected weight for gestational age, but no smaller reductions in potential fetal weight. So whether this is clinically significant is really unknown.”

Berkin added that caffeine did not significantly affect a crucial measure of fetal development – the waist size.

“Traditionally, when looking at fetal growth, waist circumference is probably the most important characteristic in predicting which fetuses are larger and which are smaller,” said Berkin. “In the calculations we use to determine fetal growth, waist circumference is weighed heavier than any other parameter.”

There are several theoretical reasons to suggest that caffeine might stunt the growth of the fetus, Gleason said.

“We know that both caffeine and its primary metabolite, paraxanthin, cross the placenta, but the fetus lacks the enzymes to break down caffeine or remove it from its system,” Gleason said. When caffeine builds up in fetal tissues, it can disrupt growth in the womb.