The Nutrition Society Paper of the Month for January 2020 is from British Journal of Nutrition and is entitled ‘Maternal dietary selenium intake is associated with increased gestational length and decreased risk for preterm delivery' by Malin Barman.
Preterm delivery (before 37 completed weeks of gestation) affects 5-13 % of all pregnancies around the world and is the leading cause of neonatal morbidity and mortality. There is no way of reliably predicting or preventing spontaneous preterm delivery, but there is an urgent need to identify modifiable factors influencing the prevalence of preterm delivery and to understand the pathways that regulate timing of birth.
Our research group recently published the first genome-wide association study, in the New England Journal of Medicine, regarding gestational length and preterm delivery. One of the genes that achieved genome-wide significance, the EEFSEC (eukaryotic elongation factor, selenocysteine tRNA specific) gene is involved in the selenium metabolism. The identification of a role of the selenocysteine pathway in preterm delivery suggests that the maternal selenium status may be important in relation to gestational duration and preterm delivery.
Selenium is an essential trace element. Its biological function is transferred via selenoproteins, such as the glutathione peroxidases and the thioredoxin reductases, that have important cellular homeostatic functions in maintaining redox status and antioxidant defense, as well as in modulating inflammatory responses. Redox status, inflammation and regulation of energy metabolism have been linked to the parturition process and risk for preterm delivery.
We used the Norwegian Mother, Father and Child Cohort Study (MoBa), a large population based pregnancy cohort, to examine the associations of maternal selenium intake from diet in pregnancy and maternal selenium status at mid-pregnancy with gestational length and spontaneous preterm delivery.
MoBa provides a unique source to study the potential effect of selenium intake on pregnancy outcomes; with about 100,000 included pregnancies, and detailed assessment of selenium intake from various sources. The data include comprehensive information about lifestyle habits, health and socioeconomic status as well as linkage to national health registries such as the National birth registry with available information about pregnancy outcomes like gestational length and preterm delivery.
We found that selenium intake from food, but not from supplements, was associated with increased gestational length and decreased risk of preterm delivery in 72,075 women included in this study. Selenium concentration in blood, available for a subsample of 2637 women, was not associated with either gestational length or risk of preterm delivery. The reason for the different effect of selenium from supplements and selenium from food may be due to that most of the women in the MoBa cohort have food-selenium intakes near or above the recommended daily intake, which is thought to guarantee an optimal selenoenzyme expression.
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