Ready-meal consumption is increasing worldwide; however, its impact on human health remains unclear. We aimed to examine the association between processed food and beverage consumption during pregnancy and pregnancy outcomes. Pregnant women were recruited for the Japan Environment and Children's Study (JECS), a nationwide, large-scale, prospective cohort study. This study included 104,102 registered children (including fetuses or embryos) and collected questionnaire-based data during the first and second/third trimester of pregnancy. Participants' medical records were transcribed at pregnancy registration, immediately after delivery, and 1 month after delivery. Logistic regression analysis was used to estimate the association between processed food consumption and pregnancy outcomes. The incidence of stillbirth was higher in the group that consumed moderate (1-2 times per week) and high (≥3-7 times per week) amounts of ready-meals (adjusted odds ratio (aOR) = 2.054, 95% confidence interval (CI): 1.442-2.926, q = 0.002; aOR = 2.632, 95% CI: 1.507-4.597, q = 0.007, respectively) or frozen meals (aOR = 2.225, 95% CI: 1.679-2.949, q < 0.001; aOR = 2.170, 95% CI: 1.418-3.322, q = 0.005, respectively) than in the group that rarely consumed such foods. Processed food consumption during pregnancy should be carefully considered.
Keywords: birth cohort; pregnancy outcome; processed foods; ready-made meals; stillbirth.