Ready-Meal Consumption During Pregnancy is a Risk Factor for Stillbirth: The Japan Environment and Children's Study (JECS)

Background: Dietary habits have changed worldwide in the past few decades, and the market for ready-made foods has increased. However, the impact of consumption of processed foods, such as beverages stored in a can or plastic bottle, on human health remains unclear. This study aimed to examine the association between processed foods and beverage consumption during pregnancy and pregnancy outcomes using data from the Japan Environment and Children Study (JECS), a national birth cohort study. Methods: The subjects consisted of 104,102 registered children (including fetuses or embryos). The study collected questionnaire-based data during the first and second/third trimester of pregnancy. Participants’ medical records were transcribed by physicians, midwives/nurses, and/or Research Coordinators at registration, immediately after delivery, and 1 month after delivery. We performed a logistic regression analysis to estimate the association between consumption of processed food and pregnancy outcomes. Findings: The incidence of stillbirth was higher in the group that consumed a moderate (1–2 times per week) and high (≥ 3-7 times per week) amount of ready-made (aOR = 2·054, 95% 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 food. In addition, the consumption of beverages increased the risk of stillbirth, as previously reported. Interpretation: Our results indicate that the consumption of processed foods during pregnancy should be carefully considered. Cooking ready-made and frozen meals in a microwave may induce unwanted chemical reactions/releases, which might result in adverse pregnancy outcomes. Funding: This research was funded by the Ministry of the Environment, Government of Japan. Declaration of Interest: The authors declare they have no competing interests. Ethical Approval: The JECS protocol was reviewed and approved by the Ministry of the Environment Institutional Review Board on Epidemiological Studies and by the Ethics Committees of all participating institutions. Written informed consent was obtained from all participants. The study was conducted in accordance with the Helsinki Declaration and other national regulations and guidelines.