No abstract available
MeSH terms
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Chorionic Gonadotropin / analysis
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Down Syndrome / diagnosis*
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Down Syndrome / diagnostic imaging*
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Female
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Gestational Age*
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Humans
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Models, Statistical
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Pregnancy
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Prenatal Diagnosis / methods*
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Risk Factors
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Ultrasonography
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alpha-Fetoproteins / analysis
Substances
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Chorionic Gonadotropin
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alpha-Fetoproteins