Premature infants have a higher risk of development disturbances. On a global scale, preterm delivery is the leading cause of death among children younger than five years of age. Pregnant women, who increase their intake of omega-3 fatty acids by taking supplements of fish oil, are able to lower their risk of preterm delivery, according to a new Cochrane review article. Earlier studies show that increased intake of oily fish can also lower the risk of preterm delivery, but it is important that the expecting mother avoids eating predatory fish such as tuna and other types of fish that are likely to contain too much mercury.
Worldwide, an estimated 15 million children are born prematurely, and around one million children die every year as a result of this. Preterm infants have an increased risk of visual disabilities, delayed physical development, and learning difficulty. A pregnancy normally lasts between 38 and 42 weeks. If a woman gives birth before the 37th week, it is considered too early. The earlier the baby arrives, the greater the risk of complications and sequelae or late effects. Therefore, one should do everything possible to ensure a healthy pregnancy, not just for the baby’s sake but also for the health and well-being of the mother.
Associate professor Philippa Middleton and a team of Cochrane scientists from Australia decided to look closer at the effect of the long-chained omega-3 fatty acids EPA and DHA that we get from oily fish and fish oil supplements.
The scientists reviewed 70 randomized studies and found that pregnant women, who increased their intake of omega-3 fatty acids had:
- 11% lower risk of giving birth before the 37th week
- 42% lower risk of giving birth before the 34th week
- 10% lower risk of giving birth to a baby that weighed less than 2,500 grams
The researchers view the study results as highly important, as there are currently no guidelines for how pregnant women can avoid giving birth too early.
It is already known that the omega-3 fatty acids, EPA and DHA, are important for the development of the infant’s brain, vision, and nervous system. It is also a fact that the intake of omega-3 fatty acids has decreased because our diets have changed.
According to Middleton, many pregnant women in Great Britain already take fish oil supplements on their own initiative – the British health authorities still don’t have a policy of recommending it.
Pregnant women should make sure to get the right types of omega-3
There are different types of omega-3 fatty acids, and Dr. Middleton points out that many fish oil supplements do not contain the right type or the optimal dosage to prevent preterm delivery. According to the new findings, it is possible to prevent preterm delivery by taking a fish oil supplement from the 12th week of pregnancy. The optimal dosage is around 1,000 mg, and DHA must represent half of that mount.
The scientists hope that their research can contribute to lowering the rate of preterm deliveries, as this is one of the largest problems for new mothers and their small infants all over the globe. Everyone can benefit from taking fish oil, not just pregnant women. The omega-3 fatty acids have a host of beneficial effects on human health.
Oily fish also lower the risk
Pregnant women with low levels of the omega-3 fatty acids EPA and DHA have a statistically significant higher risk of preterm delivery compared with pregnant women, who have higher blood levels of these two omega-3 fatty acids. This was demonstrated in a study, which scientists from Statens Serum Institut (SSI) in Copenhagen, Denmark, carried out in collaboration with colleagues from Harvard T.H. Chan School of Public Health in Boston, the United States.
The results of this study also suggest that pregnant women can lower their risk of preterm delivery significantly by eating more oily fish or by taking fish oil supplements. The study is published in Ebiomedicine (August 2018). It is also worth making a note of the fact that oily fish is a good source of selenium, a micronutrient that has been seen to prevent preterm delivery in other studies.
Caveat about mercury in oily fish
Many pregnant women are afraid to eat fish because of warnings about mercury that can damage the brain and nervous system of the fetus. The higher up in the food chain the fish is placed, the more mercury it contains. The micronutrient and trace element selenium, however, is able to neutralize mercury by binding with it and forming an inert compound called mercury selenide. Once selenium is bound to mercury, it is no longer able to support the different selenium-dependent selenoproteins that are vital for health and for a healthy pregnancy. In other words, consuming predatory fish from the top of the food chain, where there is an unfavorable mercury/selenium ratio, comes with a greater risk of getting free (unbound) mercury from the fish meat.
Eat fish from the lower part of the food chain
Pregnant women should try to avoid predatory fish like tuna, pike, perch, swordfish, shark, and halibut. Some health authorities recommend that women, who are trying to conceive, who are already pregnant, or who breastfeed, completely stay away from fresh cuts of large predatory fish like tuna, and they should also stay away from canned tuna (white tuna and albacore).
It is safer to get your essential omega-3 fatty acids from oily fish such as herring, anchovies, salmon, and mackerel, which are from the lower part of the food chain. These fish have a more favorable balance between selenium and mercury with less mercury and more selenium. However, salmon from the Baltic Sea may have a high content of heavy metals and other types of pollution, so it is better to eat salmon from cleaner waters or organically farmed salmon. High-quality fish oil supplements are also a useful solution for those, who dislike fish or simply don’t eat enough seafood.
M Makrides, L Duley, SF Olsen. Fisk oil and other prostaglandin precursor supplementation during pregnancy for reducing pre-eclampsia, preterm birth, low birth weight and intrauterine growth restriction. Cochrane review, 2018
Wiley. Omerga-3 fatty acids reduce the risk of premature birth. ScienceDaily 2018
Chris Sweeney, Harvard Gazette. Pregnant women encouraged to eat cold-water fish. MedicalXpress August 3, 2018
Nicholas V.C. Ralston, Laura J. Raymond. Mercury´s neurotoxicity is characterized by its disruption of selenium biochemistry. 2018
DR-dokumentar: De ufødte børn 03-11-2014
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