Premium
First‐trimester biochemical markers of aneuploidy and the prediction of small‐for‐gestational age fetuses
Author(s) -
Spencer K.,
Cowans N. J.,
Avgidou K.,
Molina F.,
Nicolaides K. H.
Publication year - 2008
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.5165
Subject(s) - medicine , small for gestational age , obstetrics , pregnancy associated plasma protein a , trisomy , gestation , pregnancy , aneuploidy , fetus , gestational age , odds ratio , incidence (geometry) , gynecology , first trimester , biology , chromosome , biochemistry , genetics , physics , gene , optics
Objectives To examine the clinical utility of the first‐trimester biochemical markers of aneuploidy in their ability to predict subsequent delivery of a small‐for‐gestational age (SGA) infant. Methods We examined singleton pregnancies with no chromosomal abnormality and with complete outcome data that had undergone screening for trisomy 21 by a combination of fetal nuchal translucency (NT) thickness and maternal serum free β‐human chorionic gonadotropin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A) at 11 + 0 and 13 + 6 weeks' gestation. The biochemical markers were converted to multiples of the expected normal median (MoM) for a pregnancy of the same gestation. The association between free β‐hCG and PAPP‐A and the incidence of SGA were assessed by comparing the relative incidence at MoM cut‐offs and birth‐weight centile cut‐offs. At various marker levels the likelihood ratios (LR) for SGA were also calculated after excluding other adverse pregnancy complications. Results There were 46 262 pregnancies resulting in live births with birth weight at or above the 10 th centile, and 3539 below the 10 th centile for gestation (SGA). There was a significant inverse association between the risk for SGA and maternal serum PAPP‐A MoM but not free β‐hCG MoM. At the 5 th centile of the normal outcome group for PAPP‐A (0.415 MoM) the odds ratios for SGA below the 10 th , 5 th and 3 rd centiles of normal were 2.70, 3.21 and 3.66 and the respective detection rates for SGA were 12.0%, 14.0% and 16.0%. Conclusions Low levels of maternal serum PAPP‐A are associated, in the absence of an abnormal karyotype, with an increased risk for subsequent delivery of an SGA infant. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.