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First‐trimester maternal serum level of pregnancy‐associated plasma protein‐A is an independent predictor of fetal maxillary bone length
Author(s) -
Leung T. Y.,
Chan L. W.,
Leung T. N.,
Fung T. Y.,
Sahota D. S.,
Lau T. K.
Publication year - 2006
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.2671
Subject(s) - medicine , nomogram , gestational age , pregnancy associated plasma protein a , crown rump length , fetus , gestation , pregnancy , obstetrics , nasal bone , population , prospective cohort study , gynecology , first trimester , surgery , biology , genetics , environmental health
Objective To derive a nomogram of fetal maxillary bone length (MAX) for a Chinese population and to study whether first‐trimester maternal serum levels of pregnancy‐associated plasma protein‐A (PAPP‐A) is an independent predictor of fetal MAX. Methods This was a prospective observational study over 10 months examining Chinese women with a singleton pregnancy who attended the first‐trimester screening program for Down syndrome. The subjects had the fetal crown–rump length (CRL), nuchal translucency, MAX, maternal serum PAPP‐A and free beta‐human chorionic gonadotropin (fβ‐hCG) levels measured. A nomogram of MAX was derived using normal pregnancies with reliable dates. The correlations between MAX, CRL, PAPP‐A and fβ‐hCG levels were studied, after correction for gestational dependency using Z ‐score transformation for the ultrasound markers ( Z ‐MAX and Z ‐CRL), and logarithmic transformation of multiple of gestation‐specific medians for the biochemical markers (log 10 PAPP‐A multiples of the median (MoM) and log 10 fβ‐hCG MoM), using the Pearson test and multiple regression analysis. Results During the study period, 607 Chinese women met the inclusion criteria. The mean gestational age at the first‐trimester screening was 12 + 4 weeks (SD, 4 days). Curve estimation analysis showed that a linear relationship fit best between MAX and CRL (MAX (mm) = −0.01 + 0.101 * CRL (mm) ; r = 0.826; P < 0.0001), and between MAX and gestational age (MAX (mm) = −8.465 + 0.170 * gestational age (day); r = 0.754; SD = 0.71; P < 0.0001). There were significant positive correlations between Z ‐MAX and Z ‐CRL ( r = 0.627; P = < 0.0001), Z ‐MAX and log 10 PAPP‐A MoM ( r = 0.239; P = < 0.0001). Multiple regression analysis showed that both Z ‐CRL ( P = < 0.0001) and log 10 PAPP‐A MoM ( P = 0.048) were independent predictors for Z ‐MAX. Conclusion Both CRL and maternal levels of PAPP‐A are independent predictors of the fetal MAX measured during the first trimester. The positive correlation between PAPP‐A levels and fetal MAX is consistent with the known biological function of PAPP‐A on bone growth. This association must be adjusted for when both PAPP‐A and MAX are combined for screening of Down syndrome. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.