The World Health Organisation currently suggests a limit of 300mg per day during pregnancy but some countries recommend a limit of 200mg, which can be less than a single cup of coffee from some high street cafes.
Verena Sengpiel, from Sahlgrenska University Hospital, Sweden, who led the project said: "Caffeine consumption is strongly correlated with smoking which is known to increase the risk for both pre-term delivery and the baby being small for gestational age at birth (SGA)."
