Higher Fish Intake Linked to Lower Pregnancy Hypertension Risk

A large prospective study from Japan has found that women who ate more fish before and during pregnancy had lower odds of developing hypertensive disorders of pregnancy, a group of conditions that includes gestational hypertension and preeclampsia. The research, drawn from one of the largest birth cohorts in the world, examined fish consumption as well as intake of n-3 and n-6 polyunsaturated fatty acids at two distinct time points: the year before conception and mid-to-late pregnancy. The pattern that emerged was strikingly timing-dependent. Higher fish intake before pregnancy was associated with lower odds of early-onset hypertensive disorders, while higher intake during pregnancy was associated with lower odds of the disorders overall and of late-onset disease. Because diet is one of the few potentially modifiable factors in pregnancy, the findings may have implications for preconception and prenatal nutrition, although the observational design means causation cannot be established from these data alone.

Hypertensive disorders of pregnancy are among the most common complications of gestation, affecting approximately 5 to 10 percent of pregnancies worldwide. The category encompasses gestational hypertension, in which elevated blood pressure develops during pregnancy, and preeclampsia, a more complex condition in which high blood pressure is accompanied by signs of injury to other organ systems, most often the kidneys or liver. These conditions can have serious consequences for both mothers and babies, ranging from the need for intensified monitoring and early delivery to severe maternal and neonatal complications. The distinction between early-onset and late-onset disease matters clinically, because disorders that manifest earlier in gestation generally allow less time for the pregnancy to progress safely and typically demand closer surveillance. Understanding which risk factors influence the likelihood and timing of these disorders is therefore a central concern of maternal-fetal medicine.

Fish occupies a special place in pregnancy nutrition because it is an important dietary source of long-chain n-3 polyunsaturated fatty acids. These fatty acids have been associated with cardiovascular and vascular health, partly through their anti-inflammatory effects, a mechanism of particular interest in hypertensive disorders, where vascular dysfunction and inflammation are thought to play contributing roles. Pregnancy places substantial demands on the maternal cardiovascular system, and n-3 polyunsaturated fatty acids are also recognized as nutritionally important during gestation for reasons extending beyond blood pressure. Yet despite this biological plausibility, evidence directly linking fish consumption with the risk of hypertensive disorders of pregnancy has remained limited. Most prior work has focused either on specific fatty acids in isolation or on pregnancy outcomes other than hypertension, leaving open the question of whether whole fish, as consumed in real diets, is associated with measurable differences in risk.

To address that gap, a team of researchers led by Associate Researcher Takuya Inouye from the Department of Obstetrics and Gynecology at Gunma University Graduate School of Medicine, Japan, along with Professor Eiji Yoshioka from the Department of Public Health in the Faculty of Medicine at the University of Toyama and Professor Kei Hamazaki from the Department of Public Health in the Faculty of Medicine at Gunma University Graduate School of Medicine, examined whether fish consumption before and during pregnancy was associated with the risk of hypertensive disorders of pregnancy. The study was published in Volume 65 of the European Journal of Nutrition on September 8, 2026. Explaining the motivation behind the work, Dr. Inouye said, “Given the importance of n-3 PUFAs during pregnancy, we have long been interested in how fish consumption may influence maternal and child health.”

The researchers drew on data from the Japan Environment and Children’s Study, a large nationwide prospective cohort involving 86,009 women. Prospective cohort designs of this kind follow participants forward in time, collecting exposure information before outcomes develop, which reduces the recall problems that can afflict retrospective studies. Fish consumption, along with intake of n-3 and n-6 polyunsaturated fatty acids, was assessed at two time points: during the year before pregnancy and during mid-to-late pregnancy. Participants were divided into five intake groups, or quintiles, ranging from the lowest consumers to the highest, a approach that allows researchers to compare outcomes across the full spectrum of intake rather than treating diet as a simple yes-or-no exposure. The women were then assessed for two outcomes: overall hypertensive disorders of pregnancy and early-onset hypertensive disorders of pregnancy.

The results revealed an intriguing pattern. “Higher fish intake before pregnancy was associated with lower odds of early-onset HDP, while higher intake during pregnancy was associated with lower odds of overall and late-onset HDP,” Dr. Inouye explained. Among all women, those in the highest fish-intake group before pregnancy had 34 percent lower odds of early-onset hypertensive disorders of pregnancy, with an adjusted odds ratio of 0.66. The association was even stronger among women in their first pregnancy, who had 43 percent lower odds, reflected in an adjusted odds ratio of 0.57. During pregnancy, the relationship shifted: women in the fourth fish-intake group had 14 percent lower odds of overall hypertensive disorders of pregnancy, with an adjusted odds ratio of 0.86. Higher fish intake was also associated with a 21 percent reduction in the odds of late-onset disease among women experiencing their first pregnancy, corresponding to an adjusted odds ratio of 0.79. An adjusted odds ratio below 1.0 indicates lower odds of the outcome after accounting for other measured variables, with values further from 1.0 representing stronger associations.

However, the findings were not equally strong for all dietary measures. Associations between total n-3 polyunsaturated fatty acid intake and hypertensive disorders of pregnancy were weaker and less consistent than the fish findings, suggesting that the observed relationship may not be explained simply by total n-3 polyunsaturated fatty acid intake. This discrepancy is scientifically meaningful, because it implies that something about fish as a whole food, rather than its principal fatty acids in aggregate, may underlie the association. Whole fish delivers a complex matrix of nutrients alongside its long-chain n-3 content, and the intake questionnaires captured fish as an exposure in its own right. The associations were most pronounced among women in their first pregnancy and were not statistically significant among women who had previously given birth, a pattern that may reflect genuine differences in risk between first and subsequent pregnancies or differences in how the underlying conditions develop across parity groups.

The researchers suggest the findings could have implications for preconception care and dietary counseling for women planning a pregnancy and those who are already pregnant. “Fish consumption, starting before pregnancy, should continue to be recommended as part of a healthy diet to support a healthy pregnancy,” Dr. Inouye noted. At the same time, the team is careful about what the data can and cannot show. Because this was an observational study, participants’ diets were not controlled, and the results cannot establish that fish consumption directly prevents hypertensive disorders of pregnancy. Women who eat more fish may differ from those who eat less in other ways that influence risk, and even the most carefully adjusted statistical models cannot rule out all such confounding. Further studies, including intervention trials that control fish intake directly, are needed to determine whether fish consumption itself has a beneficial effect on the risk of these disorders.

Overall, this prospective cohort study found that higher fish intake before and during pregnancy was associated with lower odds of certain forms of hypertensive disorders of pregnancy, with the timing of intake appearing to align with the timing of disease onset. While causation cannot be established from observational data, the findings support further research into fish consumption as part of healthy preconception and prenatal nutrition. The Japan Environment and Children’s Study was funded by the Ministry of the Environment, Japan, and the authors note that the findings and conclusions of the article are solely the responsibility of the researchers and do not represent the official views of the government. As intervention trials are designed to test whether increasing fish intake can genuinely lower risk, the study adds a substantial piece of evidence to the growing conversation about how maternal diet before conception and during pregnancy may shape cardiovascular outcomes for mothers and babies alike.

Subject of Research: Association of maternal fish and PUFA intake with the risk of hypertensive disorders of pregnancy in the Japan Environment and Children's Study

Article Title: Could fish consumption reduce the risk of hypertensive disorders of pregnancy?

Article References: Could fish consumption reduce the risk of hypertensive disorders of pregnancy?. Original publication (Bibliographic details unavailable.)

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Keywords: fish consumption, hypertensive disorders of pregnancy, preeclampsia, n-3 polyunsaturated fatty acids, Japan Environment and Children's Study, prenatal nutrition, fish, consumption, reduce, risk, hypertensive, disorders