Nature Neuroscience | Volume 27 | November 2024 | 2253–2260
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Resource https://doi.org/10.1038/s41593-024-01741-0
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.
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 
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).
Critically, dynamic neural changes occurred within the pregnancy 
window itself, a nuance not captured by studies limited to comparisons 
between prepregnancy and postpregnancy. For example, we observed 
large increases in white matter microstructural integrity (QA) through-
out the first and second trimesters of pregnancy, but these measures 
fully returned to baseline values by the first postpartum scan. This 
pattern may explain why previous studies report no pregnancy-related 
differences in white matter tractography14. Other measures, such as 
GMV and CT, decreased throughout gestation and displayed only a 
modest rebound postpartum. These nonlinear patterns suggest that 
only quantifying prepregnancy and postpartum brain structure may 
Whole-brain subcortical volumes
Gestation + postpartumGestation
Week Stage
Avg GMV (mm 3 ) 
0 10 20 30 Pre 1st 2nd 3rd Post
4,000
3,900
3,800
3,700
3,600
3,500
4,000
3,800
3,600
Right ventral diencephalon
Brain stem
a
CA1
Week
0 10 20 30
Stage
1,900
1,800
1,700
1,900
1,800
1,700
Avg GMV (mm 3 )
Gestation + postpartumGestation
PHCCA2/CA3
Medial temporal lobe subregion volumesb
Gestation + postpartum
Week Stage
200
180
160
200
180
160
Avg GMV (mm 3 )
GestationGestation + postpartum
Week
0 10 20 30
Stage
Pre Post
540
500
460
540
500
460
Avg GMV (mm 3 )
R2
adj  = 0.36, q = 0.031 R2
adj  = 0.41, q = 0.027 R2
adj  = 0.58, q = 0.001
Gestation
Ventral DC
T stat
Hippocampus
Putamen
Thalamus
Caudate
Lateral ventricle
–6
2
Pre 1st 2nd 3rd Post Pre Post0 10 20 30
1st 2nd 3rd 1st 2nd 3rd
Fig. 3 | Subcortical GMV changed throughout gestation. a, Multivariate 
regression analyses revealed largely negative relationships between gestation 
week and subcortical GMV regions over pregnancy, including bilateral thalamus, 
caudate, hippocampus, ventral diencephalon (encompassing hypothalamus, 
substantia nigra, mammillary body and red nucleus) and left caudate. Lateral 
ventricles displayed the only positive relationships with gestation week  
(also depicted in Fig. 1d). The whole-brain subcortical GMV estimates shown 
here were derived via FreeSurfer and ‘aseg’ subcortical segmentation. FDR-
corrected at q < 0.05. Inset, right ventral diencephalon displayed the strongest 
negative association with gestation (left; baseline—36 weeks, 19 scans) and did