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Ultrasonography, Prenatal
Karyotyping
Pregnancy Reduction, Multifetal
Pregnancy
Gestational Age
Crown-Rump Length
First Pregnancy Trimester
Retrospective Studies
Pregnancy Outcomes
Chromosome Disorders
Down's Syndrome
Chromosome Aberrations
Arthrogryposis
Anencephaly
Neck
Polyploidy
beta Subunit Human Chorionic Gonadotropin
Estriol
Pregnant Women
Dizygotic Twins
Co-Publications
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4
3
1
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