When it comes to pregnancy nutrition, most advice focuses on what to eat once you're expecting. But what about the months before? New research suggests that eating fish before pregnancy, as well as during it, may be associated with a lower risk of certain blood pressure complications.
In a study involving more than 86,000 women in Japan, researchers found that those who regularly ate fish had lower odds of developing some forms of pregnancy-related high blood pressure. The findings, published in the European Journal of Nutrition, were particularly noticeable among women experiencing their first pregnancy. However, the study doesn't prove that eating fish prevents these conditions.
Pregnancy-related high blood pressure can develop after 20 weeks and, in some cases, lead to serious complications for mothers and babies. The conditions researchers examined included gestational hypertension and preeclampsia, although the study didn't distinguish between individual diagnoses.
Researchers looked at women's reported fish consumption before pregnancy and again during pregnancy, then compared those eating habits with their medical records.
One of the more interesting findings involved timing.
Women who ate the most fish before pregnancy had 34% lower odds of developing a blood pressure disorder before 32 weeks than those who ate the least. Among first-time mothers, certain higher fish-intake groups had as much as 43% lower odds.
During pregnancy, higher fish consumption was also associated with lower odds of blood pressure complications, particularly those developing later in pregnancy. The findings were strongest among first-time mothers and weren't consistently seen among women who had previously given birth.
The relationship wasn't as simple as eating more fish for greater protection, either. Women in the highest fish-intake group didn't always have the lowest risk.
Researchers also examined omega-3 fatty acids, the beneficial fats often associated with fish. Interestingly, those results were less consistent than the findings for fish consumption itself.
That doesn't necessarily mean omega-3s weren't involved. Fish provides other nutrients, including protein, vitamins and minerals, and the researchers couldn't determine which aspects of eating fish might explain the associations. People who eat fish regularly may also have other dietary habits that affect their health.
There are limitations to consider. Women reported what they typically ate, which isn't always perfectly accurate, and the study couldn't establish whether fish consumption directly influenced their risk. The participants also lived in Japan, where eating habits may differ from those in the United States.
For American readers, fish is already recommended as part of a healthy pregnancy diet. The U.S. Food and Drug Administration and Environmental Protection Agency advise people who are pregnant or might become pregnant to eat two to three 4-ounce servings of lower-mercury fish each week. Options include salmon, sardines, trout and canned light tuna.
The new findings don't change that guidance or suggest that eating more fish will prevent pregnancy complications. But they do raise an interesting possibility: The foods we eat before pregnancy may be worth just as much attention as those we eat once we're expecting.
The Japan Environment and Children's Study was funded by Japan's Ministry of the Environment. One researcher reported receiving speaking fees from pharmaceutical and wellness companies for presentations related to omega-3 fatty acids.