Association of the maternal fish and PUFA intake with the risk of hypertensive disorders of pregnancy: a nationwide birth cohort—The Japan Environment and Children’s Study (JECS)

PURPOSE: Hypertensive disorders of pregnancy (HDP) are a leading cause of maternal and perinatal morbidity. Although n-3 polyunsaturated fatty acids (PUFAs) in fish may prevent HDP, evidence from Japanese populations, particularly regarding the preconception period, remains limited. To examine associations between fish and PUFA intake before and during pregnancy and the risk of HDP using data from a nationwide Japanese birth cohort. METHODS: This analysis included 86,009 women from the Japan Environment and Children's Study. Dietary fish and n-3/n-6 PUFAs intake was assessed using a validated food-frequency questionnaire administered in early pregnancy (median gestational age, 15.0 weeks [interquartile range (IQR) 12.0-19.0]) to capture intake before pregnancy, and in mid to late pregnancy (median gestational age, 27.0 weeks [IQR 25.0-30.0]). Participants were categorized into quintiles of intake. Logistic regression models were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for HDP, early-onset HDP (Eo-HDP < 32 weeks), and late-onset HDP (Lo-HDP ≥ 32 weeks). Missing data were addressed with multiple imputation. RESULTS: In the overall population, higher fish intake before pregnancy was associated with reduced risks of Eo-HDP in the Q5 groups, whereas higher fish intake during pregnancy was associated with reduced risks of overall HDP in Q4. In analyses restricted to nulliparous women, higher pre-pregnancy fish intake was associated with a lower risk of Eo-HDP (Q4: aOR 0.57; 95% CI 0.34-0.97; p for trend = 0.02), and higher fish intake during pregnancy was associated with a lower risk of Lo-HDP (Q4: aOR 0.79; 95% CI 0.64-0.96). Total n-3 PUFA intake showed significant associations with HDP only in some analyses. Sensitivity analyses using a 34-week cutoff yielded consistent results. CONCLUSION: Fish intake before pregnancy was associated with lower risk of Eo-HDP, whereas intake during pregnancy was linked to reduced risk of Lo-HDP. Sustained fish consumption from preconception through pregnancy may help prevent HDP and inform global nutritional guidance, including preconception care. TRIAL REGISTRATION: The Japan Environment and Children's Study, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000035091 (Registration no. UMIN000030786).