A novel prospective study conducted as part of the Odense Child Cohort in Denmark has shed light on the critical role of selenium in pregnancy and its impact on gestational diabetes mellitus (GDM) and the size of newborns. According to the findings, insufficient serum selenium levels during pregnancy, particularly a decline in glutathione peroxidase 3 (GPX3) activity, are independently correlated with a heightened risk of GDM and the likelihood of having infants classified as large for gestational age.

The study, involving 1346 pregnant females, utilized 2294 serum samples. During both early and late pregnancy, researchers measured levels of serum selenium, selenoprotein P (SELENOP), and the activity of GPX3. Additionally, assessments of fasting glucose and insulin were conducted in late pregnancy. Estimation of the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) was carried out. Furthermore, based on the WHO 2013 threshold of fasting venous plasma glucose of ≥5.1 mmol/L, GDM was defined. A subset of the cohort was subjected to an oral glucose tolerance test, and regression models, adapted for various confounding factors, were used to quantify dose-dependent link.

Key findings:

• Decline in Selenium Levels During Pregnancy: The research uncovered a decline in  selenium and SELENOP concentrations during pregnancy, emphasizing the dynamic nature of selenium status in expectant mothers.
• Dose-Dependent Relationship: The study revealed a dose-dependent inverse link of early GPX3 with late pregnancy GDM (according to WHO 2013 criteria), 2-hour glucose, fasting glucose, HOMA-IR, and insulin.
• Reduced Risk of GDM: The odds ratios (OR) for GDM were significantly lower with higher GPX3 and SELENOP levels in late pregnancy. For instance, the GDM OR was 0.33 for a 1 log-scale rise in early GPX3 activity and 0.21 for a similar rise in late pregnancy GPX3.
• Link to Offspring Size: Diminished activity of GPX3 in late pregnancy was connected with an escalated risk of large for gestational-age offspring, with approximately 20% of this connection interceded by fasting glucose concentrations.

The findings open avenues for offering selenium status assessments during pregnancy, enabling the identification of females at high risk for GDM who may benefit from selenium supplementation. Clinicians and healthcare providers may consider incorporating selenium status assessments as part of routine prenatal care, allowing for personalized approaches to mitigate the risks associated with GDM and large for gestational-age offspring. This study marks a significant advancement in maternal-fetal health research, providing valuable insights that can potentially transform prenatal care strategies and boost outcomes for both mothers and their newborns.