Wexler P, Gottesfeld K R
Obstet Gynecol. 1977 Dec;50(6):706-9.
Placental positions in 214 patients scheduled for genetic amniocentesis were reviewed. Forty-five percent were found to have ultrasound findings of a low-lying placenta or partial or total placenta previa. At term, none of these patients required intervention for bleeding or placenta previa. Parity of 4 or more, but not age, correlated with an increased incidence of partial or total placenta previa, but not with a low-lying placenta. Low-lying placenta or placenta previa may be a normal variant in early pregnancy, suggesting that failure of the placenta to relinquish this position can result in an abnormally implanted placenta at term.
对214例行遗传羊膜腔穿刺术患者的胎盘位置进行了回顾性研究。发现45%的患者超声检查结果显示胎盘低置或部分或完全前置胎盘。足月时，这些患者均无需因出血或前置胎盘而进行干预。产次为4次或更多次，但年龄与部分或完全前置胎盘的发生率增加相关，而与胎盘低置无关。胎盘低置或前置胎盘在孕早期可能是一种正常变异，提示胎盘未能放弃该位置可导致足月时胎盘植入异常。
