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The impact of fetal gender on first trimester nuchal translucency and maternal serum free β‐hCG and PAPP‐A MoM in normal and trisomy 21 pregnancies
Author(s) -
Cowans Nicholas J.,
Stamatopoulou Anastasia,
Maiz Nerea,
Spencer Kevin,
Nicolaides Kypros H.
Publication year - 2009
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.2246
Subject(s) - trisomy , fetus , obstetrics , medicine , down syndrome , gynecology , aneuploidy , pregnancy , first trimester , biology , chromosome , genetics , psychiatry , gene
Objective To investigate if fetal sex has an impact on 1st trimester combined screening for aenuploidy. Methods We studied the first trimester PAPP‐A, free β‐human chorionic gonadatropin (β‐hCG) and nuchal translucency levels in 56 024 normal, singleton pregnancies with known fetal sex at birth. We also examined the distributions in 722 pregnancies with trisomy 21 of known fetal sex. Results We have found a 14.74% increase in first trimester maternal serum (MS) median free β‐hCG MoM, 6.25% increase of PAPP‐A and a 9.41% decrease in delta NT, when the fetus was female. Analysis of data has shown that women carrying a female fetus were 1.084 times more likely to be in the ‘at risk’ group than those carrying a male fetus. In examining data from 722 pregnancies in which the fetus was affected by trisomy 21, we observed a similar 20.8% increase in free β‐hCG MoM, 5.7% increase in PAPP‐A and a 12% decrease in delta NT when the fetus was female. Amongst the trisomy 21 cases, 88.8% of male trisomy 21 cases were detected compared with 91.2% in female cases, this difference was not statistically significant. Correcting for fetal sex redressed the balance in screen‐positive rate between the sexes and had a minimal impact on detection rate. Conclusion Correcting for fetal sex may be a worthwhile consideration. A cost‐benefit analysis would be required to determine if it is feasible to introduce fetal gender assignment into the routine first trimester scan for the purpose of marker correction and whether this would have any significant impact. Copyright © 2009 John Wiley & Sons, Ltd.