title: Obstetric implications of low-lying placentas diagnosed in the second trimester.
abstract: OBJECTIVE
  To determine the obstetrical outcome of pregnancies initially complicated by a low-lying placenta in the second trimester.
  
  
  METHODS
  We reviewed the obstetric outcome of all women with singleton deliveries from 1 January 1997 to 31 March 1999 and compared the 703 women with low-lying placentas (placentas in the lower uterine segment) with the 6938 women with placentas that were normally situated in the upper uterine segment at 16-22 weeks' gestation.
  
  
  RESULTS
  Pregnancies complicated by a low-lying placenta in the second trimester were not associated with antepartum hemorrhage, preterm births, preterm prelabor rupture of membranes, pregnancy-induced hypertension, fetal growth restriction or cesarean births. However, they had a higher incidence of postpartum hemorrhage (odds ratio 1.768, 95% confidence interval 1.137, 2.748) than women with a normally situated placenta in the second trimester.
  
  
  CONCLUSIONS
  Pregnant women with low-lying placentas in the second trimester have a higher incidence of postpartum hemorrhage and hence, it would be prudent to carefully manage the third stage of labor in these women.
mesh_terms: D000328:Adult; D000367:Age Factors; D002170:Canada / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008423:Maternal Age; D010923:Placenta Previa / Q000150:complications / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D006473:Postpartum Hemorrhage / Q000453:epidemiology / Q000209:etiology; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal