High-Risk Pregnancy Is Associated With Increased Alpha-Fetoprotein Concentrations in the Amniotic Fluid and Foal Plasma.
Authors: Lanci Aliai, Mariella Jole, Ellero Nicola, Canisso Igor F, Dondi Francesco, Castagnetti Carolina
Journal: Journal of equine veterinary science
Summary
Researchers measured alpha-fetoprotein (AFP) concentrations across three groups—mares and foals with normal pregnancies delivering healthy foals, apparently normal pregnancies delivering sick foals, and high-risk pregnancies (characterised by premature udder development, placental thickening, or vulvar discharge) delivering sick foals—to determine whether AFP could serve as a marker of placental compromise and fetal distress. Amniotic fluid AFP was significantly elevated in high-risk pregnancies, and foal plasma AFP from birth to 72 hours post-partum was markedly higher in both groups delivering sick foals, with the highest concentrations in the high-risk group; a strong correlation (r = 0.84) between amniotic fluid and foal plasma AFP at birth suggested fetal urine as the primary source. When placental tissue showed histopathological lesions, AFP concentrations increased across all measured compartments—mare plasma, amniotic fluid, and foal plasma at birth, 24, and 72 hours—indicating a direct association between placental barrier compromise and AFP upregulation. For practitioners managing pregnant mares, elevated AFP in amniotic fluid obtained via transrectal ultrasound-guided aspiration or in neonatal blood samples may serve as a non-invasive biomarker for identifying placental insufficiency and predicting neonatal morbidity, potentially guiding decisions about timing of intervention or intensity of post-natal monitoring and treatment protocols.
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Practical Takeaways
- •AFP measurement in amniotic fluid and foal plasma at birth may serve as a diagnostic marker to identify high-risk pregnancies and sick foals, potentially aiding in early intervention strategies
- •Elevated AFP concentrations correlate with placental pathology and compromised placental barrier function, suggesting AFP could be useful for assessing placental health in at-risk mares
- •Mares with clinical signs of high-risk pregnancy (premature udder development, vulvar discharge, systemic illness, or increased uterine/placental thickness) warrant closer monitoring and potential AFP assessment to predict foal complications
Key Findings
- •Amniotic fluid AFP was significantly higher in high-risk pregnancies (Group 3) compared to normal pregnancies (P = 0.014)
- •Foal plasma AFP concentration was elevated from birth to 72 hours in sick foals (Groups 2 and 3), with Group 3 showing highest values
- •Strong correlation (r = 0.84; P < 0.0001) exists between amniotic fluid AFP and foal plasma AFP at birth, likely due to fetal urine contribution
- •AFP concentrations were significantly higher in pregnancies with pathologic fetal membranes across mare plasma (P = 0.031), amniotic fluid (P = 0.004), and foal plasma at birth, 24, and 72 hours (P = 0.002-0.004)