text: outstanding questions. This study and corresponding open-access 
  dataset offer neuroscientists a detailed map of the human brain across 
  gestation, a resource for which a wide range of previously unattainable 
  neurobiological questions can now be explored. 
  
  or neuron number, synaptic density and myelination (for review on 
  the latter, see ref. 4). Future studies of the relationship between fluid 
  dynamics and volumetric changes will help clarify the factors that drive 
  global neural changes during pregnancy; such insights will have broad 
  implications for maternal health (for example, neurological effects tied 
  to pre-eclampsia or edema). 
  
  Our findings from this precision imaging study show that preg- 
  nancy is characterized by reductions in GMV, cortical thinning and 
  enhanced white matter microstructural integrity that unfold week by 
  week. These changes were also tied to the significant rise in steroid hor- 
  mone concentrations over pregnancy. Some of these changes persist 
  at 2 years postpartum (for example, global reductions in GMV and CT), 
  while others, including markers of white matter integrity, appear to be 
  transient. Ventricular expansion and contraction parallel these cortical 
  changes. These widespread patterns, and the notable increase in CSF 
  volume across gestation, could reflect increased water retention and 
  subsequent compression of cortical tissue. However, the persistence 
  of these changes at 2 years postpartum and regional variation in GMV, 
  CT and QA, hint at cellular underpinnings, such as alterations in glia 