A Multicountry Analysis of Maternal Selenium Status in Pregnancy and Lactation and Infant Birth Outcomes: Findings from the Women First Maternal Preconception Study

Background: Maternal selenium deficiency is hypothesized to contribute to risk of adverse outcomes including low birth weight and prematurity, possibly through its role as an antioxidant and/or in thyroid hormone function. Objectives: We assessed relationships between maternal selenium concentrations during pregnancy with offspring outcomes including birth measurements, low birth weight (<2500 g), prematurity (<37 wk), and small for gestational age (birth weight <10th percentile for gestational age). Methods: This was a secondary analysis of the Women First Trial (NCT01883193), a randomized controlled study investigating the effect of small-quantity lipid-based nutrition supplement (sqLNS) with 130 μg selenium on fetal growth. sqLNS was started ≥3 mo prior to conception, around 12 wk of gestation, or not at all in women in Guatemala, India, and Pakistan. At 12 and 34 wk of gestation and 3 mo postpartum, maternal serum selenium was measured by inductively coupled plasma mass spectrometry (n = 145–325 per timepoint per site). We used generalized linear models adjusted for study arm, study site, and markers of inflammation to test for associations between maternal selenium status and offspring outcomes including birth anthropometry. Results: Mean selenium concentrations decreased over the course of pregnancy and were lowest 3 mo postpartum. Selenium was lowest in Pakistan and did not increase with maternal supplementation. Across all sites, we found no significant associations between maternal selenium at 12 and 34 wk with birth weight- length-, or head circumference-for-age z-scores. There were also no associations with low birth weight, small for gestational age, or prematurity. Conclusions: Maternal selenium supplementation did not impact serum concentrations, suggesting that supplementation may not overcome the impact of low intake and the high demands of pregnancy and early lactation. Larger studies in high-risk regions are needed to further clarify the relationship between maternal selenium deficiency and infant outcomes. This trial was registered at clinicaltrials.gov as NCT01883193 (registered 18 June 2013).