Division of Epidemiology and Biostatistics, Department of Family Medicine and Public Health Sciences, Wayne State University School of Medicine, Room 203, Detroit, MI 48201, USA.
Placenta. 2009 Dec;30(12):1052-7. doi: 10.1016/j.placenta.2009.09.008. Epub 2009 Oct 29.
Fetal growth depends on placental growth; the fetoplacental weight ratio (FPR) is a common proxy for the balance between fetal and placental growth. Male and female infants are known to have differing vulnerabilities in fetal life, during parturition and in infancy. We hypothesized that these differences may be paralleled by differences in how birth weight (BW) and the fetoplacental weight ratio (FPR) are affected by changes in placental proportions.
Placental proportion measures (disk shape, larger and smaller chorionic diameters, chorionic plate area calculated as the area of an ellipse with the 2 given diameters, disk thickness, cord eccentricity and cord length) were available for 24,601 participants in the Collaborative Perinatal Project delivered between >34 and <43 completed weeks. The variables were standardized and entered into multiple automated regression splines (MARS 2.0, Salford Systems, Vista CA) to identify nonlinearities in the relationships of placental growth measures to BW and FPR with results compared for male and female infants.
Changes in chorionic plate growth in female compared to male infants resulted in a greater change in BW and FPR. The positive effects of umbilical cord length on BW reversed at the mean umbilical cord length in females and at +0.08 SD in male infants.
Female infants' BW and FPR are each more responsive to changes in placental chorionic plate growth dimensions than males; this may account for greater female resilience (and greater male vulnerability) to gestational stressors. The effect of umbilical cord length on FPR may be due to longer cords carrying greater fetal vascular resistance. Again male fetuses show a higher "threshold" to the negative effects of longer cords on FPR.
胎儿的生长依赖于胎盘的生长；胎-胎盘重量比（FPR）是衡量胎儿和胎盘生长平衡的常用指标。已知男性和女性婴儿在胎儿期、分娩期和婴儿期都有不同的脆弱性。我们假设这些差异可能与出生体重（BW）和胎-胎盘重量比（FPR）受胎盘比例变化影响的方式不同有关。
在 Collaborative Perinatal Project 中，有 24601 名分娩孕周在 34 周以上至 43 周以下的参与者可提供胎盘比例测量值（盘形、较大和较小的绒毛膜直径、用给定的 2 个直径计算的绒毛膜板面积、盘厚度、脐带偏心度和脐带长度）。将变量标准化并输入到多个自动回归样条（MARS 2.0，Salford Systems，Vista CA）中，以识别胎盘生长测量值与 BW 和 FPR 之间关系的非线性，比较男性和女性婴儿的结果。
与男性婴儿相比，女性婴儿的绒毛膜板生长变化导致 BW 和 FPR 更大的变化。脐带长度对 BW 的积极影响在女性的平均脐带长度处和男性婴儿的+0.08 SD 处发生逆转。
与男性相比，女性婴儿的 BW 和 FPR 对胎盘绒毛膜板生长尺寸的变化更为敏感；这可能解释了女性对妊娠应激更具弹性（男性更脆弱）的原因。脐带长度对 FPR 的影响可能是由于携带更大胎儿血管阻力的更长脐带。同样，男性胎儿对更长脐带对 FPR 的负面影响表现出更高的“阈值”。
