懷孕婦女醫療品質 嬰兒出生體重不足 病人背景 醫院特質 病人原有的健康問題 醫療付費來源 管理式醫療服務 教學醫院 營利性醫院 嬰兒加護病房 Quality of maternity care Low birthweight delivery Patient and hospital characteristics Clinical risk factors Source of payment Managed care Teaching hospitals Hospital ownership Neonatal intensive care unit NICU