Hypertensive Disorders of Pregnancy in Relation to Coffee and Tea Consumption: The Japan Environment and Children’s Study

Background: The association between coffee/tea intake and hypertensive disorders of pregnancy (HDP) remains unclear. This study aimed to investigate the association of caffeine, coffee, and tea intake during pregnancy with the risk of HDP. Methods: We assessed this association in 85,533 singleton pregnant women with live births in the Japan Environment and Children’s Study, a prospective cohort in Japan that included women from early pregnancy onward. Caffeinated and decaffeinated coffee and tea (green, oolong, and black) consumption during pregnancy was assessed using a validated food frequency questionnaire conducted at mid-pregnancy, and caffeine intake was calculated based on coffee and tea consumption. Multivariable logistic regression was used to assess the association with the risk of HDP. Results: HDP developed in 2222 women (2.6%). Caffeine intake was weakly associated with increased risk of HDP; the multivariable odds ratio of HDP for the highest versus the lowest quartile was 1.26 (95% confidence interval: 1.11, 1.43). Coffee drinkers of two or more cups per day showed a decreased risk compared with non-drinkers (multivariable odds ratio 0.79; 0.62, 0.99) even after adjustment for total caffeine intake. Tea consumption was not associated with the risk of HDP. Conclusions: Our study suggests that higher caffeine intake may increase HDP risk, while coffee drinkers had a lower risk. Further high-quality studies are needed to replicate these findings, and to elucidate if other substances in coffee may be protective against HDP.