A multicountry analysis of maternal selenium status in Pregnancy and lactation and infant birth outcomes: Findings from the women first maternal preconception study

Authors: GILLEY, STEPHENIE - University Of Colorado; WESTCOTT, JAMIE - University Of Colorado; KEMP, JENNIFER - University Of Colorado; LONG, JULIE - University Of Colorado; HAMBRIDGE, MICHAEL - University Of Colorado; Shankar, Kartik; KREBS, NANCY - University Of Colorado

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2025
Publication Date: 12/27/2025
Citation: Gilley, S.P., Westcott, J., Kemp, J.F., Long, J., Hambridge, M., Shankar, K., Krebs, N.F., Women First Trail Group. 2025. A multicountry analysis of maternal selenium status in Pregnancy and lactation and infant birth outcomes: Findings from the women first maternal preconception study. Journal of Nutrition. 156(2). Article 101279. https://doi.org/10.1016/j.tjnut.2025.101279.
DOI: https://doi.org/10.1016/j.tjnut.2025.101279

Interpretive Summary: Selenium is a trace element with several important roles through which it may impact health. This study investigated the relationship between maternal selenium levels during pregnancy and offspring outcomes, such as birth measurements, low birth weight, prematurity, and small for gestational age. Researchers conducted a secondary analysis of the Women First trial, which included pregnant women from in areas where maternal nutrition is poor. Participants received either a small-quantity lipid-based nutrient supplement containing selenium or no supplement as part of a randomized controlled trial. Maternal selenium levels were measured at various points. Notably, in this trial maternal supplementation did not increase selenium levels. The study found no significant associations between maternal selenium concentrations at 12 and 34 weeks gestation and infant birth weight, length, or head circumference z-scores. While mothers of low birth weight infants had slightly lower selenium at 34 weeks, no link was found with prematurity. The authors conclude that maternal selenium levels do not significantly correlate with infant measurements at birth. They Further research is needed to explore potential interactions between selenium and other micronutrients.

Technical Abstract: Background: Maternal selenium deficiency may be related to risk of adverse outcomes including low birth weight and prematurity, possibly through its role as an antioxidant and/or in thyroid hormone function. Objective: We tested for relationships between maternal selenium levels during pregnancy with offspring outcomes including birth measurements, low birth weight (< 2500g), prematurity (< 37 weeks), and small for gestational age (birth weight < 10th percentile for gestational age). Methods: This is a secondary analysis of the Women First trial (NCT01883193), a randomized controlled study investigating the effect of small-quantity lipid-based nutrition supplement (sqLNS) including 130 µg selenium on fetal growth. sqLNS was started at least 3 months prior to conception, around 12 weeks of gestation, or not at all in women in Guatemala, India, and Pakistan. Gestational age was determined by first trimester ultrasound. At 12- and 34-weeks gestation and 3 months postpartum, maternal serum selenium was measured by ICP-MS (n=145-325 per timepoint per site. We used logistic or linear regression, adjusted for study arm, study site and markers of inflammation to test for associations between maternal selenium and offspring outcomes including growth measurements at birth. Results: Mean selenium levels decreased over the course of pregnancy and lactation. Selenium was lowest in Pakistan and did not increase with maternal supplementation. We found no associations between maternal selenium at 12 and 34 weeks with birth weight- length-, or head circumference-for-age z-scores. Mothers delivering infants with low birth weight had slightly lower selenium levels at 34 weeks. There was no association of maternal selenium levels with prematurity. Conclusions: We found no significant relationships between maternal selenium concentrations and infant measurements at birth. Additional research is needed to test for possible interactions between selenium and other micronutrients, such as folate and iron, on offspring outcomes.