No abstract available
MeSH terms
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Female
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Gestational Age
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Humans
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Infant Mortality
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Infant, Newborn
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Infant, Premature
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Obstetric Labor, Premature / epidemiology*
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Pregnancy
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Pregnancy Outcome / epidemiology*
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Pregnancy, Multiple / statistics & numerical data*
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Risk
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Triplets
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Twins
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United States