text: **Image processing.***Cortical volume and thickness*. CT and GMV were 
  measured with Advanced Normalization Tools54 version 2.1.0 (ANTs). 
  We first built a subject-specific template (SST) (antsMultivariateTem- 
  plateConstruction2) and tissue priors (antsCookTemplatePriors) 
  based on our participant’s two preconception whole-brain T1-weighted 
  scans to examine neuroanatomical changes relative to the participant’s 
  prepregnancy baseline. We used labels from the OASIS population 
  template, provided by ANTs, as priors for this step. For each session, 
  the structural image was processed and registered to the SST using the 
  ANTs CT pipeline (antsCorticalThickness). This begins with an N4 bias 
  field correction for field inhomogeneity, then brain extraction using a 
  hybrid registration/segmentation method55. Tissue segmentation was 
  performed using Atropos54 to create tissue masks of CSF, gray matter, 
  white matter and deep gray matter. Atropos allows prior knowledge 
  to guide the segmentation algorithm, and we used labels from our SST 
  as priors to minimize warping and remain in native participant space. 
  CT measurements were then estimated using the DiReCT algorithm56, 
  which estimates the gray–white matter interface and the gray mat- 
  ter–CSF interface and computes a diffeomorphic mapping between 
  the two interactions, from which thickness is derived. Each gray matter 
  tissue mask was normalized to the template and multiplied to a Jaco- 
  bian image that was computed via affine and nonlinear transforms. 
  Using MATLAB (version 2022a), summary, regional-level estimates 
  of CT, GMV and CSF for each scan were obtained by taking the first 
  eigenvariate (akin to a ‘weighted mean’57) across all voxels within each 
  parcel of the Schaefer 400-region atlas58. We then averaged ROIs across 
  networks, which were defined by the 17-network Schaefer scheme58,59. 
  Global measures of CT, GMV and CSF were computed for each session 
  by summing across all voxels within the respective output image; 
  total brain volume was computed by summing across all voxels within 
  each session’s brain extraction mask. Our findings held when using an 
  SST derived from all 26 MRIs (prepregnancy through postpartum), 
  as well as when estimating the mean (versus weighted mean) of all 
  voxels within each parcel. The ANTs CT pipeline is highly validated 
  with good test–retest reproducibility and improved ability to predict 
  variables such as age and gender from region-wise CT measurements 