title: Prospective assessment of fetal-maternal cell transfer in miscarriage and pregnancy termination.
abstract: BACKGROUND
  Fetal cells (microchimerism) are acquired by women during pregnancy. Fetal microchimerism persists decades later and includes cells with pluripotent capacity. Persistent microchimerism has the capacity for both beneficial and detrimental maternal health consequences. Both miscarriage and termination of pregnancy can result in fetal microchimerism. We sought to determine whether cellular fetal microchimerism is acquired during management of pregnancy loss and further explored factors that could influence fetal cell transfer, including viability of fetal tissue, surgical versus medical management and gestational age.
  
  
  METHODS
  Pregnant women (n= 150 samples from 75 women) with singleton pregnancies undergoing a TOP (n= 63) or treatment for embryonic or fetal demise (miscarriage, n= 12) were enrolled. Mononuclear cells were isolated from blood samples drawn before, and 30 min after, treatment. Fetal cellular microchimerism concentrations were determined using quantitative PCR for a Y chromosome-specific sequence, expressed as genome equivalents of fetal DNA per 100 000 maternal cell equivalents (gEq/10(5)). Detection rate ratios were determined according to clinical characteristics.
  
  
  RESULTS
  Cellular fetal microchimerism was found more often in post- compared with pretreatment samples, 24 versus 5% (P= 0.004) and at higher concentrations, 0-36 versus 0-0.7 gEq/10(5) (P< 0.001). Likelihood of microchimerism was higher in surgical than medical management, detection rate ratio 24.7 (P= 0.02). The detection rate ratio for TOP versus miscarriage was 16.7 for known male fetuses (P= 0.02). Microchimerism did not vary with gestational age.
  
  
  CONCLUSIONS
  Significant fetal cell transfer occurs during miscarriage and TOP. Exploratory analyses support relationships between obstetric clinical factors and acquisition of fetal cellular microchimerism; however, our limited sample size precludes definitive analysis of these relationships, and confirmation is needed. In addition, the long-term persistence and potential consequences of fetal microchimerism on maternal health merit further investigation.
authors: Department of Obstetrics & Gynecology,  University of Washington, Box 356460, Seattle, WA 98195-6460,  USA.
authors: S E
authors: SE
authors: Peterson
authors: J L
authors: JL
authors: Nelson
authors: K A
authors: KA
authors: Guthrie
authors: V K
authors: VK
authors: Gadi
authors: T M
authors: TM
authors: Aydelotte
authors: D J
authors: DJ
authors: Oyer
authors: S W
authors: SW
authors: Prager
authors: H S
authors: HS
authors: Gammill
mesh_terms: D000028:Abortion, Induced; D000022:Abortion, Spontaneous / Q000175:diagnosis* / Q000235:genetics; D000293:Adolescent; D000328:Adult; D046528:Chimerism; D041322:Chromosomes, Human, Y / Q000648:ultrastructure; D015331:Cohort Studies; D005260:Female; D005333:Fetus; D005865:Gestational Age; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000473:pathology; D008297:Male; D008431:Maternal-Fetal Exchange; D016133:Polymerase Chain Reaction / Q000379:methods; D011247:Pregnancy; D011446:Prospective Studies