The choice of amniotic fluid in metabolomics for the monitoring of fetus health

ABSTRACT

Amniotic fluid (AF) is a biological fluid in which metabolite transport is regulated by the placenta, the permeable skin, fetal lung egress and gastric fluid. During pregnancy, the composition of AF changes from similar to the interstitial fluid of the mother, to a more complex system, influenced by the fetus’s urine. Since AF reflects the mother’s and the fetus’s health status at the same time, it may be an important diagnostic tool for a wider spectrum of clinical conditions. Indeed, the metabolic characterization of AF in relation to pathological occurrences may lead to the discovery of new biomarkers for a better clinical practice. For this reason, metabolomics may be the most suitable strategy for this task. In this review, research works on metabolomic AF analysis are discussed according to the morbidity of interest, being preterm birth/labor, gestational age and diabetes and fetal malformations, along with a number of other important studies.

KEYWORDS:

• Metabolomics
• amniotic fluid
• NMR
• mass spectrometry
• PTB
• gestational age
• gestational diabetes
• fetal malformations
• perinatal conditions
• pregnancy

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Key issues

• Due to the diversity that characterized the different study groups, the articles on PTB and PTL do not show similar findings. However, these works describe different aspects of the variables affecting PTB and PTL.

• Regarding studies on GA determination, Bock and Cohn observed a number of discriminant metabolites and both sets of experiments agree on the higher creatinine, and the lower glutamate, valine, isoleucine, and alanine levels during the second trimester of gestation.

• In the case of GD, only Graça’s work from 2010 could provide any useful trends, being the other studies lacking in sample size or proper analytical conditions.

• Focusing on the subject of FM, the extensive study of Graça’s group delivered several according data: glutamine increase, and valine, leucine, glutamate, tyrosine, and glucose decrease seem to be a recurring pattern in all the types of malformation examined. Such trends may be explained by a reasonably enhanced protein synthesis, kidney underdevelopment, and a lesser employment of the respiratory chain pathway, which in turn causes higher gluconogenesis process. Interestingly, the article published in 2009 reported metabolites that are able to discriminate the different malformations.

• Given the variety of conditions explored in the Miscellaneous section (Section 8), it was not possible to observe a common behavior.