Subjects

756 neonates (406 males, 350 females; 356 singletons, 400 twins) between 37 and 57 weeks gestational age are included in this analysis. All children were participating in prospective longitudinal studies of early brain development being carried out at the University of North Carolina at Chapel Hill (UNC). Mothers were recruited during the second trimester of pregnancy from the outpatient obstetrics and gynecology clinics at UNC hospitals. Exclusion criteria at enrollment were the presence of abnormalities on fetal ultrasound or major medical illness in the mother. Demographic variables (maternal age, paternal age, maternal education, paternal education, maternal ethnicity, paternal ethnicity, maternal psychiatric history, paternal psychiatric history, and total household income) were collected via maternal report. For the purpose of the current study maternal psychiatric history and paternal psychiatric history were treated as binary variables. Individuals were counted as positive for psychiatric history if they reported a diagnosis in any of the following DSM-V categories, or if medical record review indicated such a diagnosis: schizophrenia spectrum and other psychotic disorders, bipolar and related disorders, depressive disorders, anxiety disorders, obsessive-compulsive and related disorders, attention-deficit hyperactivity disorders, Tourette's syndrome, or autism spectrum disorders. Medical history variables (birthweight, gestational age at birth, 5-minute APGAR scores, stay in neonatal intensive care unit over 24 h, gestation number, and delivery method) were collected from maternity and pediatric medical records shortly after birth. Maternal smoking during pregnancy was collected via maternal report at two time points during pregnancy and shortly after birth. Demographic and obstetric history data are summarized in Table ​Table1.1. Experiments were undertaken with the understanding and written consent of each subject's mother or father, with the approval of the Institutional Review Board of the UNC School of Medicine.

Descriptive statistics for demographic and medical history variables

^aDOB = date of birth.

^bLow income: at or below 200% of federal poverty level (FPL), middle income: between 200% and 400% of FPL, high income: above 400% of FPL.