In a nationwide Japanese cohort of more than 86,000 women, higher fish intake before pregnancy was associated with lower odds of early-onset hypertensive disorders of pregnancy, while fish intake during pregnancy showed different associations with late-onset disease, particularly among women who had not previously given birth. Total dietary omega-3 and omega-6 PUFA intake showed much less consistent associations, suggesting that the relationship with fish consumption may not be explained by total PUFA intake alone.