text: **Whole-brain dynamics from baseline through postpartum**
  To begin, we characterized broad neuroanatomical changes over the 
  course of the entire experimental window (baseline—2 years postpar- 
  tum, 26 scans; Fig. 1d). Generalized additive models revealed strong 
  nonlinear (effective degrees of freedom > 3) relationships between 
  weeks since conception and summary brain metrics. Total GMV 
  (*F*= 27.87,*P*< 0.001, deviance explained = 93.9%,*R*2 
  adj = 0.91), summary 
  CT (*F*= 15.79,*P*< 0.001, deviance explained = 78.6%,*R*2 
  adj = 0.75) and 
  total brain volume (*F*= 26.12,*P*< 0.001, deviance explained = 93.4%, 
  *R*2 
  adj = 0.90) linearly decreased during gestation and appeared to 
  partially rebound postpartum. In contrast, global microstructural 
  integrity (QA) of white matter increased throughout the first and sec- 
  ond trimesters before returning to baseline levels in the postpartum 
  period (whole-brain QA,*F*= 4.62,*P*= 0.007, deviance explained = 60.2%, 
  *R*2 
  adj = 0.51). We also observed nonlinear patterns of lateral ventricle 
  expansion*(F*= 10.44,*P*< 0.001, deviance explained = 83.8%,*R*2 
  adj = 0.77) 
  and increased cerebrospinal fluid (CSF;*F*= 13.32,*P*< 0.001, deviance 
  explained = 83.8%,*R*2 
  adj = 0.79) rising in the second and third trimesters 
  before dropping sharply postpartum. 