By Steven Reinberg
MONDAY, April 23, 2018 (HealthDay News) -- There's new evidence that even moderate amounts of caffeine consumed by a mom-to-be might affect her child's weight years later.
The overall effect was small -- an average of an extra pound by age 8. But children of women who consumed the most caffeine during pregnancy were 66 percent more likely to be slightly overweight, researchers found.
"The results support the current recommendations to limit caffeine intake during pregnancy to less than 200 milligrams [mg] of caffeine per day, which is approximately two to three cups of black coffee," said lead researcher Eleni Papadopoulou. She is from the department of environmental exposure and epidemiology at the Norwegian Institute of Public Health in Oslo.
"However, we found associations with caffeine intake also with intake below 200 mg," she said.
Although this study cannot prove that caffeine itself causes kids to gain excess weight, it begs the question whether women should avoid caffeine altogether during pregnancy, Papadopoulou pointed out.
It is important that pregnant women be aware that caffeine does not come from coffee only, but also from sodas and energy drinks, which can contribute a lot of caffeine to daily consumption, she said.
And one expert noted that caffeine itself may not be the culprit, since many of the women in the study consumed it by drinking sodas and eating candy.
"Our study does not have the right design to draw conclusions on a safe threshold of caffeine intake during pregnancy," Papadopoulou said. "But we add to the growing body of evidence indicating that complete avoidance of caffeine during pregnancy might be advisable."
In the study of nearly 51,000 women and their babies, average caffeine consumption during pregnancy was tied to a 15 percent higher risk of a child gaining excess weight. High caffeine consumption was linked to a 30 percent higher risk, the researchers found.
And prenatal exposure to any level of caffeine was associated with a child's greater risk of being overweight at ages 3 and 5 years.
This excess weight gain lasted only for 8-year-olds whose mothers consumed very high levels of caffeine during pregnancy.
Very high levels of caffeine consumption during pregnancy were linked with less than a pound of excess weight up to age 5, but slightly over a pound by age 8, the researchers reported.
"Maternal caffeine intake may modify the overall weight growth trajectory of the child from birth to 8 years," the researchers wrote.
"The results add supporting evidence for the current advice to reduce caffeine intake during pregnancy and indicate that complete avoidance might actually be advisable," the study authors concluded.
For the study, Papadopoulou's team asked women who had been pregnant for 22 weeks how much caffeine they consumed.
Sources of caffeine included coffee, black tea, caffeinated sodas and energy drinks, chocolate, chocolate milk, sandwich spreads, desserts, cakes and candy.
The women were grouped by the amount of caffeine they consumed daily: 0 to 49 mg was considered low; 50 to 199 mg was average; 200 to 299 mg was high; and 300 mg or more was considered very high.
The researchers kept track of the children's weight, height and body length up to age 8.
Among the women, 46 percent were classified as low caffeine users, 44 percent as average, 7 percent as high and 3 percent as very high.
Women who consumed high amounts of caffeine were more likely to be older than 30, have more than one child, consume more calories and smoke during pregnancy, the findings showed.
In addition, women with a very high caffeine intake were more likely to be poorly educated and have been obese before pregnancy, the investigators found.
Dr. Mitchell Roslin, chief of obesity surgery at Lenox Hill Hospital in New York City, disagreed that caffeine is the reason for the weight gain seen among the children in the study.
"It's likely that caffeine is not good for you, especially in high doses," he said.
"But the effect of caffeine seen in this study is more likely due to what the caffeine is in, rather than a result of caffeine itself," Roslin suggested.
Much of the caffeine women consumed came from sugar-sweetened drinks and candy, he noted.
"If you can't separate the caffeine from the sugar, it's hard to prove that it's the caffeine that's the problem," Roslin explained.
"My guess is that if they did the same study with black coffee, where sugar had been eliminated, the results would not be the same," Roslin said.
The report was published online April 23 in the journal BMJ Open.