Individual tracts
Corpus Callosum
R inf. fronto occipital fasc.
Gestation + postpartum
Summary white matter tracts
Gestation
StageStage
L inf. longitudinal fasc.
L arcuate fasciculus
Pre 1st 2nd 3rd Post
AF
C
CC
CS
IFOF
ILF
CPT
CST
DT
MLF
Pre 1st 2nd 3rd PostPre 1st 2nd 3rd Post
Pre 1st 2nd 3rd Post
2
1
0
–1
–2
2
1
0
–1
–2
2
1
0
–1
–2
2
1
0
–1
–2
Fig. 4 | White matter microstructure changes throughout the experiment. 
a, Numerous white matter tracts demonstrate increasing QA in relation to 
advancing gestation week (baseline—36 weeks, 16 scans), as determined by 
correlational tractography analysis (FDR, q < 0.0001). See Supplementary 
Table 9 for complete list of tracts with a significant correlation between QA and 
gestation week. b, Summary of QA values by pregnancy stage (gestation and 
postpartum, 23 scans) for representative ROIs significantly tied to gestation. 
ROI-based tractometry was used to extract QA values. Each boxplot represents 
IQR for each stage, with a horizontal line representing the median value. The 
whiskers indicate variability outside (±1.5) of this range. Outside values are >1.5× 
and <3× IQR beyond either end of the box. Values were z scored and transformed 
to have a mean of zero and s.d. of one for easier comparison across individual 
tracts. AF , arcuate fasciculus; C, cingulum bundle; CC, corpus callosum; CPT, 
corticopontine tracts; CS, corticostriatal tracts; CST, corticospinal tracts; DT, 
dentatorubrothalamic tract; IFOF , inferior frontal occipital fasciculus; ILF , 
inferior longitudinal fasciculus; MLF , middle longitudinal fasciculus.