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Screening for trisomy 21 in twin pregnancies in the first trimester: does chorionicity impact on maternal serum free β‐hCG or PAPP‐A levels?
Author(s) -
Spencer Kevin
Publication year - 2001
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/pd.152
Subject(s) - trisomy , obstetrics , monochorionic twins , twin pregnancy , medicine , pregnancy associated plasma protein a , gestation , gynecology , pregnancy , first trimester , fetus , aneuploidy , biology , biochemistry , genetics , gene , chromosome
Abstract In a study of 180 twin pregnancies I have examined the distribution of maternal serum free β‐human chorionic gonadotrophin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A), in addition to fetal nuchal translucency thickness (NT), in twins classified as monochorionic or dichorionic, based on ultrasound appearance at 10–14 weeks of gestation. In 45 monochorionic and 135 dichorionic twin pregnancies the median MoM free β‐hCG was not significantly different (1.00 vs 1.01), whilst that for PAPP‐A was lower (0.89 vs 1.01) but again with no statistical significance. Previous reports of an increased fetal NT in monochorionic twins pregnancies could not be confirmed (1.03 vs 1.00). It is concluded that the existing pseudo risk twin correction algorithm is appropriate for both monochorionic and dichorionic twins in providing accurate first trimester risks for trisomy 21. Copyright © 2001 John Wiley & Sons, Ltd.