First trimester screening for Down syndrome in rhesus negative women

• Published in: Prenatal diagnosis 2008-05, Vol.28 (5), p.404-407
• Main Authors: Muhcu, Murat, Mungen, Ercument, Atay, Vedat, Ipcioglu, Osman Metin, Dundar, Ozgur, Ergur, Rustu, Yergok, Yusuf Ziya
• Format: Article
• Language: English
• Subjects: biochemical markers; Biological and medical sciences; Biomarkers - blood; Chorionic Gonadotropin, beta Subunit, Human - blood; Cohort Studies; Delivery. Postpartum. Lactation; Down Syndrome - blood; Down Syndrome - diagnosis; Female; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Gynecology. Andrology. Obstetrics; Humans; Male; Medical sciences; Molecular and cellular biology; Pregnancy; Pregnancy Trimester, First; Pregnancy-Associated Plasma Protein-A - analysis; Prenatal Diagnosis; prenatal screening; Retrospective Studies; Rh-Hr Blood-Group System - blood; rhesus negative blood group
• ISSN: 0197-3851; 1097-0223
• DOI: 10.1002/pd.1970

Objectives To explore the effect of maternal rhesus status on first‐trimester screening markers for Down syndrome. Methods We accessed a database of singleton pregnancies undergoing first‐trimester genetic screen with maternal Rh status documented and pregnancy outcome information available. Excluded were cases of fetal chromosomal or structural abnormalities, or maternal systemic disease. Results of maternal serum pregnancy‐associated plasma protein A (PAPP‐A) and β‐human chorionic gonadotrophin (β‐hCG) adjusted for gestational age were compared between Rh‐negative and Rh‐positive women with p < 0.05 considered significant. Results Two thousand two hundred and two pregnancies fulfilled the study criteria, and 160 of them (7%) were Rh negative. Only free β‐hCG corrected multiples of the median (MoM) values were statistically increased in Rh‐negative women (p < 0.009). Using a cut‐off of 1:300, screen‐positive rates of maternal serum biochemistry were not significantly different between Rh‐negative and Rh‐positive women (12.5 vs 10.4%, p = 0.41). Conclusion The present study focused on measurements of β‐hCG and PAPP‐A in the sera of women with Rh‐negative blood group. Women with Rh‐negative blood type have similar first‐trimester serum PAPP‐A MoM values as Rh‐positive women, but significantly higher β‐hCG MoM values. However, there was no significant difference in the screen‐positive rate for Down syndrome between the two groups. Copyright © 2008 John Wiley & Sons, Ltd.