Department of Obstetrics and Gynaecology, School of Population and Public Health, University of British Columbia and the Children's and Women's Hospital and Health Centre of British Columbia, Kelowna, Canada.
PLoS One. 2020 Nov 30;15(11):e0238673. doi: 10.1371/journal.pone.0238673. eCollection 2020.
The relationship between several intriguing perinatal phenomena, namely, modal, optimal, and relative birthweight and gestational age, remains poorly understood, especially the mechanism by which relative birthweight and gestational age resolve the paradox of intersecting perinatal mortality curves.
Birthweight and gestational age distributions and birthweight- and gestational age-specific perinatal death rates of low- and high-risk cohorts in the United States, 2004-2015, were estimated using births-based and extended fetuses-at-risk formulations. The relationships between these births-based distributions and rates, and the first derivatives of fetuses-at-risk birth and perinatal death rates were examined in order to assess how the rate of change in fetuses-at-risk rates affects gestational age distributions and births-based perinatal death rate patterns.
Modal gestational age typically exceeded optimal gestational age because both were influenced by the peak in the first derivative of the birth rate, while optimal gestational age was additionally influenced by the point at which the first derivative of the fetuses-at-risk perinatal death rate showed a sharp increase in late gestation. The clustering and correlation between modal and optimal gestational age within cohorts, the higher perinatal death rate at optimal gestational age among higher-risk cohorts, and the symmetric left-shift in births-based gestational age-specific perinatal death rates in higher-risk cohorts explained how relative gestational age resolved the paradox of intersecting perinatal mortality curves.
Changes in the first derivative of the fetuses-at-risk birth and perinatal death rates underlie several births-based perinatal phenomena and this explanation further unifies the fetuses-at-risk and births-based models of perinatal death.
几种引人关注的围产期现象，即模态、最佳和相对出生体重与胎龄之间的关系，仍未得到很好的理解，尤其是相对出生体重和胎龄如何解决相交围产死亡率曲线的悖论的机制。
使用基于出生的和扩展的胎儿风险公式，估计了美国 2004-2015 年低危和高危队列的出生体重和胎龄分布以及出生体重和胎龄特异性围产儿死亡率。检查了这些基于出生的分布和比率与胎儿风险出生率和围产儿死亡率的一阶导数之间的关系，以评估胎儿风险率变化的速度如何影响胎龄分布和基于出生的围产儿死亡率模式。
模态胎龄通常超过最佳胎龄，因为两者都受到出生率一阶导数的峰值的影响，而最佳胎龄还受到胎儿风险率的一阶导数在晚期急剧增加的点的影响。在队列内模态和最佳胎龄的聚类和相关性、高危队列中最佳胎龄的围产儿死亡率较高，以及高危队列中基于出生的胎龄特异性围产儿死亡率的对称左移，解释了相对胎龄如何解决相交围产死亡率曲线的悖论。
胎儿风险出生率和围产儿死亡率的一阶导数的变化是基于出生的几种围产现象的基础，这种解释进一步统一了胎儿风险和基于出生的围产儿死亡模型。
