Eating Fish During Pregnancy? Lower Risk of Preterm Birth

Consuming fish rich in Omega-3 at least once a week during pregnancy may reduce the risk of preterm birth. Additionally, eating 3 portions per week could promote a higher birth weight. A diet including the right amount of seafood is therefore recommended during pregnancy.

This emerges from a study conducted by researchers at the University of Crete and published in the American Journal of Nutrition.

Fish During Pregnancy: Yes or No?

The consumption of fish containing the Omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) is associated with a reduced risk of neurological and visual developmental defects in the fetus. However, the presence of harmful contaminants, such as methylmercury, polychlorinated biphenyls (PCBs), and dioxins, has led many people in recent years to exclude fish from their diet or to take purified fish oil supplements. Methylmercury is a toxic molecule easily absorbed by tissues and harmful to the heart and nervous system. PCBs are carcinogenic compounds used in industrial and commercial processes until 1977.

They are now banned but may still be present in some foods. Dioxins are a group of toxic components that affect the endocrine and immune systems. In any case, as specified by official guidelines from the U.S. Department of Agriculture (USDA), consuming a variety of fish and seafood is recommended for a healthy diet. The USDA advises pregnant women, breastfeeding mothers, women planning pregnancy, and children under 12 to consume fish in safe amounts—about 340 grams per week, including 170 grams of canned white tuna—while avoiding species high in mercury such as swordfish, shark, and king mackerel.

Positive Effects on Child Health

The research reviewed 19 European studies including a total of 151,880 mother-child pairs. Data analysis showed that women who consumed fish more than once a week during pregnancy had an 11–13% lower risk of preterm birth compared to those who ate fish less frequently.

Mothers who ate fish at least 1 or 2 times a week gave birth to babies weighing on average 8.9 grams more than those who did not consume any fish. Baby weight was 15.2 grams higher when mothers consumed at least 3 portions of fish per week.

Positive Effects of Omega-3 Rich Fish

The results suggest a positive effect of fish on birth weight and full gestation. According to the researchers, these effects are due to the action of EPA and DHA. This hypothesis is supported by the fact that the most marked results on newborn weight were observed in women who consumed fatty fish, which contain higher amounts of Omega-3.

During pregnancy, maternal serum loses high concentrations of DHA, and the synthesis of polyunsaturated fatty acids in the placenta and fetus is very low. Maternal Omega-3 levels and placental function are essential for adequate fetal supply. This study may help settle the debate on fish consumption during pregnancy, suggesting that women consume it in appropriate amounts.

 Source: Vasiliki Leventakou et al. "Fish intake during pregnancy, fetal growth, and gestational length in 19 European birth cohort studies" Am J Clin Nutr 2014 99: 3 506-516; First published online December 11, 2013.