title: Differences in placental telomere length suggest a link between racial disparities in birth outcomes and cellular aging.
abstract: BACKGROUND
  Health disparities begin early in life and persist across the life course. Despite current efforts, black women exhibit greater risk for pregnancy complications and negative perinatal outcomes compared with white women. The placenta, which is a complex multi-tissue organ, serves as the primary transducer of bidirectional information between the mother and fetus. Altered placental function is linked to multiple racially disparate pregnancy complications; however, little is known about racial differences in molecular factors within the placenta. Several pregnancy complications, which include preeclampsia and fetal growth restriction, exhibit racial disparities and are associated with shorter placental telomere length, which is an indicator of cellular stress and aging. Cellular senescence and telomere dynamics are linked to the molecular mechanisms that are associated with the onset of labor and parturition. Further, racial differences in telomere length are found in a range of different peripheral tissues. Together these factors suggest that exploration of racial differences in telomere length of the placenta may provide novel mechanistic insight into racial disparities in birth outcomes.
  
  
  OBJECTIVE
  This study examined whether telomere length measured in 4 distinct fetally derived tissues were significantly different between black and white women. The study had 2 hypotheses: (1) that telomere length that is measured in different placental tissue types would be correlated and (2) that across all sampled tissues telomere length would differ by race.
  
  
  METHODS
  In a prospective study, placental tissue samples were collected from the amnion, chorion, villus, and umbilical cord from black and white singleton pregnancies (N=46). Telomere length was determined with the use of monochrome multiplex quantitative real-time polymerase chain reaction in each placental tissue. Demographic and pregnancy-related data were also collected. Descriptive statistics characterized the sample overall and among black and white women separately. The overall impact of race was assessed by multilevel mixed-effects linear regression models that included empirically relevant covariates.
  
  
  RESULTS
  Telomere length was correlated significantly across all placental tissues. Pairwise analyses of placental tissue telomere length revealed significantly longer telomere length in the amnion compared with the chorion (t=-2.06; P=.043). Overall telomere length measured in placenta samples from black mothers were significantly shorter than those from white mothers (β=-0.09; P=.04). Controlling for relevant maternal and infant characteristics strengthened the significance of the observed racial differences (β=-0.12; P=.02). Within tissue analyses revealed that the greatest difference by race was found in chorionic telomere length (t=-2.81; P=.007).
  
  
  CONCLUSIONS
  These findings provide the first evidence of racial differences in placental telomere length. Telomere length was significantly shorter in placental samples from black mothers compared with white mothers. Given previous studies that have reported that telomere length, cellular senescence, and telomere dynamics are molecular factors that contribute to the rupture of the amniotic sac, onset of labor, and parturition, our findings of shorter telomere length in placentas from black mothers suggest that accelerated cellular aging across placental tissues may be relevant to the increased risk of preterm delivery in black pregnancies. Our results suggest that racial differences in cellular aging in the placenta contribute to the earliest roots of health disparities.
authors.affiliation: Tulane Brain Institute, Tulane University, New Orleans, LA.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Jones
authors.affiliation: Department of Obstetrics and Gynecology, Tulane University School of Medicine, New Orleans, LA.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Gambala
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Tulane University School of Medicine, New Orleans, LA.
authors.forename: Kyle C
authors.initials: KC
authors.lastname: Esteves
authors.affiliation: Department of Global Community Health and Behavioral Sciences, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA.
authors.forename: Maeve
authors.initials: M
authors.lastname: Wallace
authors.affiliation: Tulane Brain Institute, Tulane University, New Orleans, LA.
authors.forename: Reid
authors.initials: R
authors.lastname: Schlesinger
authors.affiliation: Tulane Brain Institute, Tulane University, New Orleans, LA.
authors.forename: Marguerite
authors.initials: M
authors.lastname: O'Quinn
authors.affiliation: Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, LA.
authors.forename: Laura
authors.initials: L
authors.lastname: Kidd
authors.affiliation: Department of Global Community Health and Behavioral Sciences, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA.
authors.forename: Katherine P
authors.initials: KP
authors.lastname: Theall
authors.affiliation: Tulane Brain Institute, Tulane University, New Orleans, LA; Department of Psychiatry and Behavioral Sciences, Tulane University School of Medicine, New Orleans, LA. Electronic address: sdrury@tulane.edu.
authors.forename: Stacy S
authors.initials: SS
authors.lastname: Drury
mesh_terms: D000328:Adult; D001741:Black or African American; D016922:Cellular Senescence; D005260:Female; D054624:Health Status Disparities; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010920:Placenta; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D016615:Telomere / Q000648:ultrastructure*; D059505:Telomere Homeostasis; D044465:White People
keywords: cellular aging; health disparity; placenta; pregnancy complication; race; telomere length