The association between placental histopathology and autism spectrum disorder. 
Research suggests that autism spectrum disorder (ASD) has its origins in utero.  This study examines the association between evidence of placental histopathology and ASD.  Administrative claims data and medical records data were used to identify ASD cases (N = 55) and matched controls (N = 199) born at New York Methodist Hospital between 2007 and 2014 and subsequently seen in affiliated pediatrics clinics.  Placentas from all births during this time period were reviewed as part of routine care.  Data were analyzed using conditional logistic regression to account for the matched (gender, gestational age, and birth weight) design.  Acute placental inflammation, regardless of type was associated with an increased risk of ASD (odds ratio [OR] = 3.14, 95% CI = 1.39, 6.95).  Chronic uteroplacental vasculitis (OR = 7.13; 95% CI = 1.17, 43.38), the fetal inflammatory response in the chorionic plate vessels (OR = 5.12; 95% CI = 2.02, 12.96), and maternal vascular malperfusion pathology (OR = 12.29; 95% CI = 1.37, 110.69) were associated with an increased risk of ASD.  Placental villous edema was associated with a decreased risk of ASD (OR = 0.05; 95% CI = 0.0005, 0.42).  In subanalyses among male placentas acute inflammation overall, fetal inflammatory response in the chorionic plate vessels, and maternal vascular malperfusion pathology remained significantly associated with an increased risk of ASD whereas placental villous edema remained associated with a decreased risk of ASD.  Histologic evidence of placental inflammation and maternal vascular malperfusion pathology are associated with ASD.