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Pregnancy
Gestational Age
Crown-Rump Length
Ultrasonography, Prenatal
First Pregnancy Trimester
Sensitivity and Specificity
Second Pregnancy Trimester
Prospective Studies
Maternal Age
Risk Factors
Placenta
Neck
Newborn Infant
Small for Gestational Age Infant
Down's Syndrome
Pregnancy Complications
Pre-Eclampsia
Fetal Diseases
Single Nucleotide Polymorphism
beta Subunit Human Chorionic Gonadotropin
Co-Publications
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28
20
8
5
4
3
2
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