The research implications of the selection of a gestational age estimation method
The research implications of the selection of a gestational age estimation method
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DOI：
10.1111/j.1365-3016.2007.00865.x
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发表时间：
2007-09-01
影响因子：
2.8
通讯作者：
Zhang, Jun
中科院分区：
文献类型：
--
作者：
Lynch, Courtney D.;Zhang, Jun
估计孕周的方法主要有三种：基于月经末期(LMP)的测年法、基于超声波的测年法和新生儿估计法。我们回顾了每种方法的优点和局限性，以及它们对研究的影响。基于LMP的测年是一种简单、低成本的估计孕周的方法。与使用月经日期相关的限制包括报告问题，如LMP日期的不确定性，可能是由于与月经无关的出血，以及对排卵延迟发生率的担忧，这可能导致对怀孕的无效估计，即使对某些LMP日期的女性也是如此。鉴于大多数美国女性在怀孕期间至少有一次超声波检查，临床医生使用早期超声波来验证月经日期正变得越来越普遍。为了使用超声波计算孕周，需要将胎儿的测量结果与特定胎龄的参考值进行比较。这种方法的主要局限性是，对对称性大小胎儿的胎龄估计会有偏差。此外，鉴于超声参考是使用根据可靠的LMP日期确定日期的怀孕开发的，它们可能与根据LMP计算的日期在同一方向上存在偏见。新生儿对胎龄的估计已被证明是最不精确的年代测定方法。为了强调选择妊娠测年方法的研究意义，我们使用了常规产前超声诊断成像研究的数据来确定过期分娩的危险因素。过期分娩的风险因素根据妊娠测年方法的选择而有所不同，这表明一些发现是选择方法的人为结果，而不是因果关系的证据。
There are three primary methods of gestational age estimation: dating based on last menstrual period (LMP), ultrasound-based dating and neonatal estimates. We review the strengths and limitations of each method as well as their implications for research. Dating based on LMP is a simple, low-cost method of estimating gestational age. Limitations associated with the use of menstrual-based dating include reporting problems such as uncertainty regarding the LMP date, possibly due to bleeding not associated with menses, as well as concerns about the incidence of delayed ovulation, which can result in invalid estimates of gestation, even for women with certain LMP dates. Given that most women in the US have at least one ultrasound during pregnancy, it is becoming increasingly common for clinicians to verify menstrual dates using early ultrasound. To calculate gestational age with the use of ultrasound, fetal measurements are compared with a gestational age-specific reference. The primary limitation of this method is the fact that the gestational age estimates of symmetrically large or small fetuses will be biased. Further, given that ultrasound references were developed using pregnancies that were dated according to reliable LMP dates, they are potentially biased in the same direction as dates calculated according to LMP. Neonatal estimates of gestational age have been shown to be the least precise dating method. To highlight the research implications of the choice of a gestational dating method, we used data from the Routine Antenatal Diagnostic Imaging with Ultrasound Study to identify risk factors for post-term delivery. Risk factors for post-term delivery are shown to vary according to the choice of a gestational dating method, suggesting that some findings are an artefact of the choice of a method rather than evidence of causality.