First trimester maternal serum ischaemia-modified albumin: a marker of hypoxia-ischaemia-driven early trophoblast development

BACKGROUND: A hypoxic intrauterine environment is believed to play a pivotal role in physiological trophoblast development. Ischaemia-modified albumin (IMA) is used in the measurement of cardiac ischaemia. We aimed to test the hypothesis that maternal serum IMA may be elevated in early pregnancy as a measurable manifestation of intrauterine ischaemia. METHODS: Prospective observational study in healthy women with singleton pregnancies (n=66) and non-pregnant controls (n=26). Maternal serum IMA levels were measured at 11-13 weeks of gestation and in non-pregnant women. RESULTS: The median IMA level in the pregnant group [115.14 kU/l; interquartile range (IQR) 102.33-124.71 kU/l] was significantly higher (P<0.001) than in non-pregnant controls (73.71 kU/l; IQR 60.38-82.78 kU/l). During pregnancy, absolute values of IMA were higher than the concentration used for the diagnosis of myocardial ischaemia (>95 kU/l) in 86% of women. CONCLUSIONS: In early pregnancy, IMA levels were above the concentration used for the diagnosis of myocardial ischaemia in most women, and should therefore not be used as a marker for cardiac ischaemia in pregnancy. Maternal serum IMA is elevated to supra-physiological levels in early normal pregnancy supporting the hypothesis that normal trophoblast development is associated with a hypoxic intrauterine environment, although other mechanisms leading to an IMA increase cannot be excluded.