随着妊娠进展,早期妊娠观察到的前置胎盘可能会迁移至正常位置。这并不是真正的迁移,而是胎盘上端出现不同于下端的差别性生长。在大约 15 至 20 周时,约 85% 的胎盘为前置胎盘,而在 20 至 23 周时仍然存在的前置胎盘,约有三分之一在即将分娩时恢复到正常位置。[38]Dashe JS, McIntire DD, Ramus RM, et al. Persistence of placenta previa according to gestational age at ultrasound detection. Obstet Gynecol. 2002;99:692-697.http://www.ncbi.nlm.nih.gov/pubmed/11978274?tool=bestpractice.com[49]Oppenheimer L, Holmes P, Simpson N, et al. Diagnosis of low-lying placenta: can migration in the third trimester predict outcome? Ultrasound Obstet Gynecol. 2001;18:100-102.http://www.ncbi.nlm.nih.gov/pubmed/11529986?tool=bestpractice.com[50]Predanic M, Perni SC, Baergen RN, et al. A sonographic assessment of different patterns of placenta previa "migration" in the third trimester of pregnancy. J Ultrasound Med. 2005;24:773-780.http://www.ncbi.nlm.nih.gov/pubmed/15914681?tool=bestpractice.com[51]Olive EC, Roberts CL, Nassar N, et al. Test characteristics of placental location screening by transabdominal ultrasound at 18-20 weeks. Ultrasound Obstet Gynecol. 2006;28:944-949.http://www.ncbi.nlm.nih.gov/pubmed/17121427?tool=bestpractice.com[70]Becker RH, Vonk R, Mende BC, et al. The relevance of placental location at 20-23 gestational weeks for prediction of placenta previa at delivery: evaluation of 8650 cases. Ultrasound Obstet Gynecol. 2001;17:496-501.http://www.ncbi.nlm.nih.gov/pubmed/11422970?tool=bestpractice.com
孕妇预后
孕妇预后通常良好。接受择期和急诊剖宫产手术的患者,都存在与这种手术相关的并发症风险。[71]Bergholt T, Stenderup JK, Vedsted-Jakobsen A, et al. Intraoperative surgical complication during cesarean section: an observational study of the incidence and risk factors. Acta Obstet Gynecol Scand. 2003;82:251-256.http://www.ncbi.nlm.nih.gov/pubmed/12694122?tool=bestpractice.com 前置胎盘患者接受输血的风险增加(因为术前、术中和术后出血),并且存在与输血相关的风险(因地区而异)。[72]Magan EF, Evans S, Hutchinson M, et al. Postpartum hemorrhage after cesarean delivery: an analysis of risk factors. South Med J. 2005;98:681-685.http://www.ncbi.nlm.nih.gov/pubmed/16108235?tool=bestpractice.com 这些妊娠女性接受剖宫产子宫切除术的风险也增加了,但这个风险仍然较低 (0.2%)。[73]Watanasomsiri N, Rungruxsrivorn T, Chaithongwongwatthana S. Risk factors for cesarean hysterectomy in cesarean delivery. J Med Assoc Thai. 2006;89(suppl 4):S100-S104.http://www.ncbi.nlm.nih.gov/pubmed/17725146?tool=bestpractice.com[74]Daskalakis G, Anastasakis E, Papantoniou, et al. Emergency obstetric hysterectomy. Acta Obstet Gynecol Scand. 2007;86:223-227.http://www.ncbi.nlm.nih.gov/pubmed/17364287?tool=bestpractice.com
在后续妊娠中出现前置胎盘的风险也增加了,但这个风险仍然较低 (< 1%)。[75]Yang Q, Wen SW, Oppenheimer L, et al. Association of caesarean delivery for first birth with placenta praevia and placental abruption in second pregnancy. BJOG. 2007;114:609-613.http://www.ncbi.nlm.nih.gov/pubmed/17355267?tool=bestpractice.com[76]Kennare, R, Tucker G, Heard A, et al. Risks of adverse outcomes in the next birth after a first cesarean delivery. Obstet Gynecol. 2007;109:270-276.http://www.ncbi.nlm.nih.gov/pubmed/17267823?tool=bestpractice.com 在后续妊娠中,需要进行剖宫产的病例显著增加。[77]American College of Obstetricians and Gynecologists. Vaginal birth after previous cesarean delivery: ACOG Practice Bulletin, No. 54. Obstet Gynecol. 2004;104:203-212.http://www.ncbi.nlm.nih.gov/pubmed/15229039?tool=bestpractice.com
相对部分性前置胎盘而言,完全性前置胎盘的预后可能较差。[78]Tuzovic L. Complete versus incomplete placenta previa and obstetric outcome. Int J Gynaecol Obstet. 2006;93:110-117.http://www.ncbi.nlm.nih.gov/pubmed/16563394?tool=bestpractice.com
胎儿预后
胎儿预后一般良好,但过度出血和宫内生长受限可能对胎儿造成损伤。[79]Koifman A, Levy A, Zaulan Y, et al. The clinical significance of bleeding during the second trimester of pregnancy. Arch Gynecol Obstet. 2008;278:47-51.http://www.ncbi.nlm.nih.gov/pubmed/18066562?tool=bestpractice.com[80]Ananth CV, Demissie K, Smulian JC, et al. Relationship among placenta previa, fetal growth restriction, and preterm delivery: a population-based study. Obstet Gynecol. 2001;98:299-306.http://www.ncbi.nlm.nih.gov/pubmed/11506849?tool=bestpractice.com[81]Ananth CV, Smulian JC, Vintzileos AM. The effect of placenta previa on neonatal mortality: a population-based study in the United States, 1989 through 1997. Am J Obstet Gynecol. 2003;188:1299-1304.http://www.ncbi.nlm.nih.gov/pubmed/12748502?tool=bestpractice.com
新生儿预后
新生儿预后取决于早产的程度以及能否获得专业的新生儿护理。[81]Ananth CV, Smulian JC, Vintzileos AM. The effect of placenta previa on neonatal mortality: a population-based study in the United States, 1989 through 1997. Am J Obstet Gynecol. 2003;188:1299-1304.http://www.ncbi.nlm.nih.gov/pubmed/12748502?tool=bestpractice.com[82]Salihu HM, Li QL, Rouse DJ, et al. Placenta previa: neonatal death after live births in the United States. Am J Obstet Gynecol. 2003;188:1305-1309.http://www.ncbi.nlm.nih.gov/pubmed/12748503?tool=bestpractice.com[83]Lal AK, Hibbard JU. Placenta previa: an outcome-based cohort study in a contemporary obstetric population. Arch Gynecol Obstet. 2015;292:299-305.http://www.ncbi.nlm.nih.gov/pubmed/25638449?tool=bestpractice.com 还受到分娩前出血程度的影响,此情况可导致新生儿贫血。[79]Koifman A, Levy A, Zaulan Y, et al. The clinical significance of bleeding during the second trimester of pregnancy. Arch Gynecol Obstet. 2008;278:47-51.http://www.ncbi.nlm.nih.gov/pubmed/18066562?tool=bestpractice.com[80]Ananth CV, Demissie K, Smulian JC, et al. Relationship among placenta previa, fetal growth restriction, and preterm delivery: a population-based study. Obstet Gynecol. 2001;98:299-306.http://www.ncbi.nlm.nih.gov/pubmed/11506849?tool=bestpractice.com
相对部分性前置胎盘而言,完全性前置胎盘的预后可能较差。[78]Tuzovic L. Complete versus incomplete placenta previa and obstetric outcome. Int J Gynaecol Obstet. 2006;93:110-117.http://www.ncbi.nlm.nih.gov/pubmed/16563394?tool=bestpractice.com
婴儿猝死综合征的风险可能轻度升高。[84]Li DK, Wi S. Maternal placental abnormality and the risk of sudden infant death syndrome. Am J Epidemiol. 1999;149:608-611.https://academic.oup.com/aje/article/149/7/608/167983/Maternal-Placental-Abnormality-and-the-Risk-ofhttp://www.ncbi.nlm.nih.gov/pubmed/10192307?tool=bestpractice.com