Presented at the Neonatal Society 2007 Spring Meeting.
Mather J, Mistry H, Ramsay MM, Broughton-Pipkin F, Symonds ME
Centre for Reproduction and Early Life, School of Human Development, University of Nottingham, Queen’s Medical Centre, Nottingham NG9 2UH, UK
Background: Elevated homocysteine (HCy) in the circulation is one potential risk factor for oxidative stress and endothelial dysfunction, alterations associated with pre-eclampsia (PE). Reduced plasma folate may also occur in PE, therefore potentially contributing to elevated HCy. It could then result in fetal compromise and intrauterine growth restriction an adaptation that may then be exacerbated as a consequence of defective placental transfer.
Objective: To compare the concentration of HCy and folate in the maternal plasma of women with normotensive or pre-eclamptic pregnancies, taken at the time of delivery. In addition simultaneous umbilical venous plasma samples were analysed in order to gain an index of insufficient placental transfer of HCy in PE.
Study Design: A hospital based cross sectional study was set up. Ethical approval was gained from the Hospital Ethics Committee of QMC, Nottingham and written informed consent obtained from all participants. Normotensive pregnancies were the control group (n=27) and pre-eclamptics (n=25) the study group. Both maternal and umbilical venous plasma samples were collected. The definition criteria for PE were a resting blood pressure of 140/90mmHg or greater combined with proteinuria of 300mg/L or greater on two separate occasions at least 6 hours apart after 20 weeks gestation. HCy concentrations were measured using the Abbott Axsym System Fluorescence Polarisation Immunoassay technique (1). Folate concentrations were measured via a microbiological assay (2).
Results:
There was no difference in either maternal or umbilical venous plasma HCy or folate between groups. In normotensive pregnancies, both HCy (p<0.005) and folate (p<0.001) concentrations were higher in umbilical compared to maternal plasma. There was no significant relationship between folate and HCy concentrations. For pre-eclamptic pregnancies, only plasma folate concentrations were higher in umbilical plasma (p<0.001) and they were negatively correlated to plasma HCy (r = 0.669, p= 0.005). A similar relationship was found in maternal samples but this was not significant (r = 0.369, p = 0.076).
Conclusions: In this study, normotensive and PE pregnancies cannot be distinguished on the basis of maternal or umbilical plasma concentrations of HCy or folate. Paired analysis of maternal and umbilical plasma samples suggested a possible defect in the placental transfer of HCy in PE, which requires further investigation.
Acknowledgements:
References
1. Shipchandler, M.T. and E.G. Moore. Clin Chem, 1995. 41(7): p. 991-4.
2. Molloy, A.M. and J.M. Scott. Methods in Enzymology. 1997. p. 43-53.