While alcohol is a big no-no for pregnant women, coffee is usually tolerated if you keep the amount of caffeine to 200mg a day, which is about two mugs of instant coffee.
Yet, unfortunately, a new study might make you want to reconsider your beloved morning cup.
Researchers found out that even moderate coffee consumption during pregnancy, one to two cups per day, could increase the risk of obesity in school age children.
It has not been clearly shown if caffeine is the direct cause, but the relationship, alone, has caused researchers to encourage increased caution.
"There may be good cause to increase the restriction of the recommended maximum of three cups of coffee per day. Caffeine is not a medicine that needs to be consumed," says Verena Sengpiel, Associate Professor in obstetrics and gynecology at Sahlgrenska Academy, Sweden, and specialist physician at the Department of Obstetrics and Gynecology at Sahlgrenska University Hospital.
Published in the BMJ Open journal, the study issued by scientists at Sahlgrenska Academy, in collaboration with the Norwegian Institute of Public Health, examined information on 50,943 pregnant women, in one of the world's largest health surveys of pregnant women, the Norwegian Mother and Child Cohort Study (MoBa). Children were then followed until eight years of age.
The results show that children born to mothers who consumed caffeine during pregnancy are at greater risk of being overweight at preschool and school ages. At 5-years-old for instance, there was a 5 per cent difference between the group whose mothers had the highest caffeine consumption compared to those whose mothers had the lowest caffeine consumption.
Coffee isn't the only caffeine provider and this study included coffee, tea, chocolate, energy drinks and other sources.
"In the Nordic countries, coffee is the primary source, while, women in, for example, England receive the greatest amount of caffeine from black tea. If you look at mothers in the younger age group, it comes from energy drinks. We included different sources in the study and found a similar association between caffeine consumption from these different sources and children's growth," says Verena Sengpiel.
While more studies are needed to understand the full meaning of these results, "caffeine is a substance that you can choose to reduce consumption of or completely refrain from during pregnancy", Sengpiel concluded.