Lackman F, Capewell V, Gagnon R, Richardson B
Department of Obstetrics and Gynaecology, Canadian Institutes of Health Research Group in Fetal and Neonatal Health and Development, University of Western Ontario, London.
Am J Obstet Gynecol. 2001 Sep;185(3):674-82. doi: 10.1067/mob.2001.116686.
Our purpose was to examine regulatory linkages between fetal oxygenation and fetal and placental growth. We determined umbilical cord PO (2) and oxygen saturation, fractional oxygen extraction, and birth to placental weight ratio values in relation to size at birth for a large tertiary hospital population delivering at term.
The computerized perinatal database of St Joseph's Health Care London, London, Ontario, was used to obtain the umbilical cord gases, pH, birth weight, placental weight, and other selected information for all term, singleton, liveborn infants between January 1990 and December 1999 (N = 27,043). Oxygen saturation values were calculated from the umbilical cord PO(2) and pH data with a previously derived empirical equation; fractional oxygen extraction values were calculated from the umbilical cord oxygen saturation data. Size at birth was divided into the following 5 birth weight categories using neonatal growth standards: fetal growth restriction, <3%; borderline fetal growth restriction, >or=3% and <10%; appropriate for gestational age, >or=10% and <or=90%; borderline large for gestational age, >90% and <or=97%; large for gestational age, >97%.
Infants in the borderline fetal growth restriction and fetal growth restriction groups had umbilical vein and artery PO(2) and oxygen saturation values that were stepwise lower than respective values for infants in the appropriate for gestational age group. Conversely, infants in the borderline large for gestational age and large for gestational age groups had umbilical vein PO(2) and oxygen saturation values that were stepwise higher than respective appropriate for gestational age group values; infants in these groups showed no change in arterial PO (2) and oxygen saturation values. Therefore infants in the borderline fetal growth restriction and fetal growth restriction groups had fractional oxygen extraction values that were stepwise higher than the appropriate for gestational age group value, whereas values for infants in the borderline large for gestational age and large for gestational age groups remained unchanged. Birth weight was disproportional to placental weight for infants in the borderline fetal growth restriction and fetal growth restriction groups when compared with that of the infants in the appropriate for gestational age group, with the birth to placental weight ratio values stepwise decreased. Conversely, birth weight was proportional to placental weight for infants in the borderline large for gestational age and large for gestational age groups with the birth to placental weight ratio values thus unchanged when compared with that of the infants in the appropriate for gestational age group.
We conclude that fetal oxygenation is related to size at birth across the entire range of birth weights as studied at term from macrosomic to growth-restricted infants; this conclusion supports oxygen as a primary determinant of fetal growth. However, there are differences in the linkage between fetal oxygenation and metabolic rate or growth for these cohort groups that may relate to underlying etiologic processes.
我们的目的是研究胎儿氧合与胎儿及胎盘生长之间的调节联系。我们测定了一所大型三级医院足月分娩的大量人群的脐带血氧分压（PO₂）、氧饱和度、氧摄取分数以及出生体重与胎盘重量比值，并将这些值与出生时的大小相关联。
使用安大略省伦敦市圣约瑟夫医疗保健中心的计算机化围产期数据库，获取1990年1月至1999年12月期间所有足月、单胎、活产婴儿的脐带血气、pH值、出生体重、胎盘重量及其他选定信息（N = 27,043）。利用先前推导的经验公式，根据脐带PO₂和pH数据计算氧饱和度值；根据脐带氧饱和度数据计算氧摄取分数值。根据新生儿生长标准，将出生时的大小分为以下5个出生体重类别：胎儿生长受限，<3%；边缘性胎儿生长受限，≥3%且<10%；适于胎龄，≥10%且≤90%；边缘性大于胎龄，>90%且≤97%；大于胎龄，>97%。
边缘性胎儿生长受限组和胎儿生长受限组婴儿的脐静脉和脐动脉PO₂及氧饱和度值逐步低于适于胎龄组婴儿的相应值。相反，边缘性大于胎龄组和大于胎龄组婴儿的脐静脉PO₂及氧饱和度值逐步高于适于胎龄组婴儿的相应值；这些组婴儿的动脉PO₂及氧饱和度值无变化。因此，边缘性胎儿生长受限组和胎儿生长受限组婴儿的氧摄取分数值逐步高于适于胎龄组的值，而边缘性大于胎龄组和大于胎龄组婴儿的值保持不变。与适于胎龄组婴儿相比，边缘性胎儿生长受限组和胎儿生长受限组婴儿的出生体重与胎盘重量不成比例，出生体重与胎盘重量比值逐步降低。相反，边缘性大于胎龄组和大于胎龄组婴儿的出生体重与胎盘重量成比例，与适于胎龄组婴儿相比，出生体重与胎盘重量比值无变化。
我们得出结论，在足月研究的从巨大儿到生长受限婴儿的整个出生体重范围内，胎儿氧合与出生时的大小相关；这一结论支持氧是胎儿生长的主要决定因素。然而，这些队列组在胎儿氧合与代谢率或生长之间的联系存在差异，这可能与潜在的病因学过程有关。
