Division of Reproductive Health, Centers for Disease Control and Prevention, Atlanta, Georgia 30341, USA.
Am J Epidemiol. 2010 Apr 1;171(7):826-36. doi: 10.1093/aje/kwp468. Epub 2010 Feb 25.
Population-based standards for infant size for gestational age depend on accurate assessments of birth weight and gestational age; the accuracy of the latter measure has been questioned. The authors sought to explore how different methods of assigning gestational age in vital records data affect distributions of birth weight for gestational age. The 2005 US natality file was used to create 4 measures of gestational age for singleton births consisting of measures found on the 1989 (last menstrual period (LMP) and clinical estimate) and 2003 (LMP and obstetric estimate) revisions of the US standard birth certificate: clinical or obstetric estimate and LMP-based estimate agree within 7 days ("gold standard"); clinical estimate only; obstetric estimate only; and LMP-based estimate only. Birth weight for gestational age distributions differed according to the measurement of gestational age. Regardless of birth certificate revision, the median, 10th, and 90th percentile distributions were virtually identical for the gold standard, clinical estimate, and obstetric estimate. Birth weights for the LMP estimate were higher for preterm births and lower for postterm births for both birth certificate revisions. Agreement between the gold standard estimate and clinical and obstetric estimates of gestational age suggests that using the LMP-based estimate for establishing norms should be revisited.
基于人群的胎龄相关婴儿大小标准取决于对出生体重和胎龄的准确评估；后者的准确性一直受到质疑。作者试图探讨生命记录数据中不同的胎龄赋值方法如何影响胎龄相关出生体重的分布。利用 2005 年美国出生率文件，为单胎出生创建了 4 种胎龄测量方法，包括美国标准出生证明 1989 年（末次月经（LMP）和临床估计）和 2003 年（LMP 和产科估计）修订版中的测量方法：临床或产科估计与 LMP 估计相差 7 天以内（“金标准”）；仅临床估计；仅产科估计；以及仅 LMP 估计。胎龄相关的出生体重分布因胎龄测量方法而异。无论出生证明修订版如何，金标准、临床估计和产科估计的中位数、第 10 百分位数和第 90 百分位数分布几乎相同。对于这两个出生证明修订版，LMP 估计的出生体重对于早产较高，对于过期产较低。金标准估计与临床和产科胎龄估计之间的一致性表明，应重新考虑使用 LMP 估计来建立规范。
