Evidence for Extracellular Superoxide Dismutase (SOD3), Glutathione and Redox Dynamics in Amniotic Fluid Throughout Gestation

Introduction: Amniotic fluid (AF) plays a pivotal role in foetal gastrointestinal development by delivering bioactive factors that support intestinal maturation. However, the redox environment of AF and its potential contribution to foetal intestinal homeostasis remain insufficiently characterised. This study aimed to quantify key antioxidant markers—superoxide dismutase isoforms (SOD1, SOD3), glutathione (GSH), and the oxidative DNA damage marker 8-hydroxy-2-deoxyguanosine (8-OHdG)—in AF across gestational ages and compare them with those in human milk (HM). Methods: AF samples (n = 60) were collected from pregnancies between 15 and 40 weeks of gestation, grouped into preterm (<37 weeks) and term (≥37 weeks). SOD1, SOD3, GSH, and 8-OHdG concentrations were quantified using ELISA. HM samples (n = 45) were similarly analysed. Results: SOD1 and SOD3 in AF concentrations decreased significantly with gestational age (GA) (p < 0.001), while 8-OHdG levels increased (p < 0.001). SOD3 showed a negative correlation with 8-OHdG (p = 0.004). HM contained significantly higher levels of both SOD isoforms compared to AF (AF vs. HM: 35.6 (1.9–172.3) vs. 267.9 (54.6–843.8), p < 0.001 for SOD1 and 1.2 ng/mL (0.1–26.5) vs. 5.5 ng/mL (0.1–300.0), p < 0.001 for SOD3), regardless of GA. Conclusions: Our findings highlight the dynamic nature of the redox environment in AF and its potential importance for foetal GIT development. The disruption of redox balance by preterm birth or inadequate AF intake during foetal life may have long-term consequences for intestinal development and function. These insights provide a foundation for future clinical studies aimed at enhancing neonatal feeding regimens, particularly for preterm infants and those with congenital gastrointestinal disorders.