Antenatal coffee and tea consumption and the effect on birth outcome and hypertensive pregnancy disorders

Background and objective: Coffee and tea are commonly consumed during pregnancy. While several of their components, like caffeine, have strong pharmacological effects, the effect on the unborn fetus remains unclear. Caffeine intake has been associated with abortion, preterm birth and fetal growth restriction, but a general consensus on caffeine restriction is still lacking. We aimed to investigate antenatal coffee, tea and caffeine consumption and the effect on birth weight and length, gestational age at birth and hypertensive disorders in pregnancy. Methods: A total of 936 healthy pregnancies from the WHISTLER birth cohort with data on coffee and tea consumption were included. Maternal and child characteristics as well as antenatal coffee and tea consumption were obtained through postpartum questionnaires. Reported consumption was validated using available preconceptional data. Caffeine intake was calculated from coffee and tea consumption. Linear and logistic regression was used to assess the association with birth outcome and hypertensive disorders. Results: After adjustment for smoking and maternal age, a daily consumption of more than 300mg of caffeine compared to less than 100mg of caffeine was significantly associated with an increased gestational age (linear regression coefficient = 2.00 days, 95%CI = 0.12-4.21, P = 0.03). Tea consumption was significantly related to a higher risk of pregnancy induced hypertension (OR = 1.13, 95%CI = 1.04-1.23, P = 0.004). No associations concerning coffee consumption or birth weight and birth length were observed. Conclusions: Daily caffeine consumption of more than 300mg is possibly associated with an increase in gestational age at birth. A possible relation between high tea consumption and increased risk for pregnancy induced hypertension warrants further research. For most outcomes, we found no significant associations with coffee or tea intake.