<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0300-9041</journal-id>
<journal-title><![CDATA[Ginecología y obstetricia de México]]></journal-title>
<abbrev-journal-title><![CDATA[Ginecol. obstet. Méx.]]></abbrev-journal-title>
<issn>0300-9041</issn>
<publisher>
<publisher-name><![CDATA[Federación Mexicana de Colegios de Obstetricia y Ginecología A.C.]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0300-90412017001200787</article-id>
<article-id pub-id-type="doi">10.24245/gom.v85i12.994</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Corrección de medianas de la fracción beta libre de gonadotrofina coriónica humana y proteína plasmática A del embarazo del primer trimestre para una muestra de población mexicana]]></article-title>
<article-title xml:lang="en"><![CDATA[Medians correction of free beta subunit of human chorionic gonadotropin and pregnancy-associated plasma protein-A during the first trimester for a Mexican population sample]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Oviedo-Cruz]]></surname>
<given-names><![CDATA[H]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Reyes-Mendoza]]></surname>
<given-names><![CDATA[MA]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Mestizo-Reyes]]></surname>
<given-names><![CDATA[V]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Centro Médico para Atención Fetal Especializada  ]]></institution>
<addr-line><![CDATA[Ciudad de México ]]></addr-line>
</aff>
<aff id="Af2">
<institution><![CDATA[,Centro Médico para Atención Fetal Especializada  ]]></institution>
<addr-line><![CDATA[Ciudad de México ]]></addr-line>
</aff>
<aff id="Af3">
<institution><![CDATA[,Centro Médico para Atención Fetal Especializada  ]]></institution>
<addr-line><![CDATA[Ciudad de México ]]></addr-line>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>00</month>
<year>2017</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>00</month>
<year>2017</year>
</pub-date>
<volume>85</volume>
<numero>12</numero>
<fpage>787</fpage>
<lpage>798</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0300-90412017001200787&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0300-90412017001200787&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0300-90412017001200787&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen  Objetivo: determinar si en una muestra de población mexicana la distribución de los marcadores séricos del primer trimestre difiere del modelo de riesgos de The Fetal Medicine Foundation y calcular los factores de corrección necesarios para un desempeño adecuado de la prueba.  Materiales y Métodos:  estudio descriptivo y transversal en el que se midieron las concentraciones de beta-hCG-libre y proteína plasmática A del embarazo en sueros maternos del primer trimestre, por ensayo de electroquimioluminiscencia aprobado por la Fetal Medicine Foundation. Se obtuvieron los múltiplos de mediana ajustados por el algoritmo de la Fetal Medicine Foundation (astraia). Para describir la distribución de cada marcador y probar su diferencia estadística con la media 0.000, se hizo su transformación a log10 ideal mediante la prueba de t para una muestra. Además, se describen las distribuciones de los múltiplos de mediana por características del embarazo y lote de reactivo.  Resultados: en 1008 sueros, el log10 MoM global fue de -0.121 ± 0.2706 para beta-hCG-libre y -0.049 ± 0.2372 para proteína plasmática A del embarazo.  Conclusiones: en esta muestra poblacional mexicana las distribuciones de beta-hCG-libre y proteína plasmática A del embarazo difieren de las esperadas para población similar a la hispana europea. Se recomienda aplicar los respectivos factores de corrección de 0.756 y de 0.893 para las medianas del algoritmo.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract  Objective: To determine whether first trimester serum markers distribution on a Mexican population sample differ from The Fetal Medicine Foundation (FMF) risks model, and to calculate the necessary correction factors for accurate test performance.  Materials and Method:  Transverse descriptive study, Free-beta-hCG and PAPP-A were measured on unselected first trimester maternal sera using FMF approved electrochemiluminescence assay, the adjusted MoM were obtained from FMF algorithm (astraia); they were log10 transformed to describe each marker distribution and to test their statistical difference with the 0.000 ideal mean by one sample t-test. MoM distributions for pregnancy characteristics and reagent lot are additionally described.  Results: On 1008 sera, the overall adjusted log10MoM was -0.121 ± 0.2706 SD for Free-beta-hCG and -0.049 ± 0.2372 SD for PAPP-A; these distributions differed significantly from tåzhe expected by FMF risks model.  Conclusions: Free-beta-hCG and PAPP-A distributions on this Mexican population sample differ from expected for population similar to Hispanic European, median correction factors of 0.756 MoM and of 0.893 MoM, respectively, are recommended for the algorithm.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[aneuploidias]]></kwd>
<kwd lng="es"><![CDATA[&#946;-hCG-libre]]></kwd>
<kwd lng="es"><![CDATA[tamizaje combinado]]></kwd>
<kwd lng="es"><![CDATA[tamizaje de trisomía 21]]></kwd>
<kwd lng="es"><![CDATA[tamizaje de preclampsia en el primer trimestre]]></kwd>
<kwd lng="en"><![CDATA[Aneuploidies]]></kwd>
<kwd lng="en"><![CDATA[Free-beta-hCG]]></kwd>
<kwd lng="en"><![CDATA[Combined screening]]></kwd>
<kwd lng="en"><![CDATA[Trisomy 21 screening]]></kwd>
<kwd lng="en"><![CDATA[First trimester screening preeclampsia]]></kwd>
</kwd-group>
</article-meta>
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