Higher intakes of fish during pregnancy may lead to infants with a higher birth weight, as well as reducing the risk of pre-term births, according to data from 19 European birth cohort studies
Eating at least one serving of fish per week during pregnancy was associated with a reduction in the risk of pre-term birth between 11% and 13%, report researchers in the American Journal of Clinical Nutrition.
Data from an impressive 151,880 mother-child pairs also indicated that women who ate fish at least three times per week gave birth to babies with birth weight about 15 grams greater than babies of women who ate less than one serving per week.
“Available data from European birth cohort studies indicate that moderate fish intake during pregnancy is associated with lower risk of preterm birth and a small but significant increase in birth weight,” wrote the authors, led by Leda Chatzi from the University of Crete.
“Although these findings cannot establish causality, they support the need for public health advice to promote fish consumption in pregnant women in accordance with country-specific restrictions regarding fish species and items known to have high concentrations of pollutants.”
The researchers said that the potential benefit of fish consumption may be linked to the omega-3 long-chain PUFAs content, with this possibility was supported by the fact that the most-pronounced effect on birth weight was observed for fatty fish types, which are rich in the omega-3s EPA and DHA
“Pregnancy is associated with a reduction in the maternal serum DHA percentage and its possible depletion in the maternal store. Because the synthesis of n23 LCPUFAs in the fetus and placenta is low, both the maternal status and placental function are critical for their supply to the fetus,” they said.
It is also possible that the benefits of omega-3 fatty acids for vascular health may also play a role, said the researchers, with more blood flow to the placenta boosting the growth of the fetus.
Regular consumption of fish and seafood, particularly varieties high in omega-3 fatty acids DHA and EPA, have been linked to a reduced risk of heart disease, neurological function in unborn babies - as well as several other benefits including eye health and joint health.
But reports that the presence of contaminants methylmercury, PCBs and dioxins in fish could be harmful to human health have caused confusion - despite the official US Department of Agriculture (USDA) line that most people should include a variety of fish and seafood in their diets. For pregnant and nursing women, those who may become pregnant, and children under 12, the USDA says that two 12 oz (340g) portions of fish per week (including 6 oz of white canned tuna but excluding certain high-mercury species such as shark, tilefish, swordfish and king mackerel) are safe.
Methylmercury is a form of the naturally occurring heavy metal that is readily absorbed by tissues and has been thought to have a detrimental effect on heart and neurological health. Now-banned PCBs (synthetic organocholorine compounds) that were used in industrial and commercial processes until 1977 but are still present in food sources in small amounts are understood to be carcinogenic.
Faced with conflicting and confusing opinions, some consumers have chosen to avoid fish altogether. Others opt to take purified omega-3 supplements or functional foods (often billed as purified or contaminant-free) instead.
Commenting on the new study, Harry Rice, PhD, VP of Regulatory & Scientific Affairs for GOED, told us: “Results from this study put us one step closer to ending the ridiculous debate about whether or not fish consumption during pregnancy is detrimental or beneficial to the unborn fetus. Pregnant women need to be encouraged to increase their intake of fatty fish during pregnancy. This should be treated as a public health, not a political, issue.”