An Investigation of Maternal Serum Pregnancy Protein Markers in the First Trimester

McCaw, Gary (1993) An Investigation of Maternal Serum Pregnancy Protein Markers in the First Trimester. Master in Management Studies thesis, University of Glasgow.

Abstract

It is well established that abnormally high levels of maternal serum alpha-foeto protein (msAFP) are associated, in the second trimester, with pregnancies affected by open neural tube defects (NTDs). More recently, low levels of msAFP, low levels of unconjugated oestriol (UE3), and high levels of human chorionic gonadotrophin (HCG) have been associated with trisomy 21 pregnancies and this, in conjunction with the known correlation between trisomy 21 and maternal age risk, has been used as the basis for population screening in the second trimester. However, screening at this stage of pregnancy carries the inherent disadvantages of late diagnosis and thus late termination of affected pregnancies. This study set out to investigate the levels of the above three analytes (AFP, HCG, UE3), in maternal serum sampled from pregnancies in the first trimester, to determine their potential as detectors of trisomy 21 and NTDs at this stage of foetal development. From the results it is clear that biochemical screening for NTDs in the first trimester is not reliable using these analytes and a separate program to screen for NTDs in the second trimester will continue to be necessary. With regard to Down's syndrome pregnancies, in this study, intact HCG varied little from the median value in trisomy 21 pregnancies in the first trimester suggesting that it may not be useful in a screening program. It can also be seen that the median MoMs for AFP and UE3 in this group are virtually identical and significantly reduced. However, there is some correlation between these markers (Correlation Coefficient r=0.22) indicating that they cannot be used as independent measures of risk in the first trimester. However, more recent studies indicate that the use of a free beta-HCG assay, rather than intact HCG, greatly improves first trimester screening efficiency having a median MoM of 1.96 in trisomy 21 pregnancies. Thus, using a combination of AFP, or UE3, free beta-HCG and maternal age, screening for chromosomal abnormalities at any gestation from 7 to 20 weeks may be possible. (Abstract shortened by ProQuest.).

• Item Type: Thesis (Master in Management Studies)
• Qualification Level: Masters
• Additional Information: Adviser: David A Aitken
• Keywords: Biochemistry, Obstetrics, Medical ethics
• Date of Award: 1993
• Depositing User: Enlighten Team
• Unique ID: glathesis:1993-75617
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Nov 2019 19:16
• Last Modified: 19 Nov 2019 19:16
• URI: https://theses.gla.ac.uk/id/eprint/75617