Pregnant women have previously been advised to limit caffeine intake, but the researchers now wonder whether to totally cut the stimulant out.
New European research has found that a moderate to high intake of caffeine during pregnancy could be linked to excess weight gain in children.
Kids who were exposed to very high levels of caffeine while in the womb had a 66% increased risk of being overweight in their early childhood, while those exposed to moderate and high levels of caffeine had a 15% to 30% increased risk of gaining excess weight prematurely.
But now a study has suggested that pregnant women should also lay off the coffee while expecting.
But the observational study did not provide a clear cause and effect.
Researchers found higher caffeine levels linked to mothers older than 30, who had more than one child, consumed more daily calories and smoked during pregnancy.
In the latest study, experts examined data from more than 50,000 Norwegian women and their babies by taking information from dietary surveys conducted in pregnancy and comparing them to child growth measurements, including weight.
"However, the link between in utero caffeine exposure and excess growth in infancy is yet to be studied, even though excess infant growth is an established risk factor in the etiology of obesity and cardiometabolic disease".
Women with a very high caffeine intake during their pregnancy were also more likely to be poorly educated and to have been obese before they got pregnant.
Children prenatally exposed to caffeine intake 200mg/day had consistently higher weight.
Sources of caffeine in the study included coffee, black tea, caffeinated soft drinks, energy drinks, chocolate, chocolate milk, sandwich spreads; and desserts, cakes, and candies.
Just under half of the mums-to-be (46%) were classified as low caffeine intake; 44 percent as average intake; 7 percent as high; and 3 percent as very high.
"The evidence provided in the study for a causal effect is extremely weak and the statement from the authors that "complete avoidance might actually be advisable" seems unjustified, particularly when we consider the effects that such a restriction might have on wellbeing of mothers".
"Women must note that coffee and tea aren't the only source of caffeine, as it's often present in chocolates, sodas and some pain relief medicines". Researchers assessed infant weight gain by calculating the difference in sex-adjusted World Health Organization weight-for-age z scores between birth and age 1 year, using reported weights, and determined childhood overweight, including obesity, at two time points at ages 3 and 5 years and once at age 8 years.
"Severe side effects have been observed among patients consuming high dose of caffeine through energy drinks".
During pregnancy, elimination of caffeine is prolonged, rapidly passing all biological membranes, including the blood-brain and placenta barriers, exposing the foetus.
"Some of the risks with excessive caffeine could be miscarriage, premature birth or smaller babies for their gestational age", said Dr Raquel Loja Vitorino, a specialist in obstetrics and gynaecology at Brightpoint Royal Women's Hospital, Abu Dhabi. However, this study was not able to determine whether the increase in growth rate in the first year of life was due to an increase in bone and muscle mass, which tends to occur earlier, or body fat which occurs later.