Neurobiological Changes Across Pregnancy: A Longitudinal Investigation

Pregnancy is a period of profound biological transformation. However, we know remarkably little about pregnancy-related brain changes. To address this gap, we charted longitudinal changes in brain structure during pregnancy and explored potential mechanisms driving these changes. Ten participants (Mean age = 28.97 years) were assessed 1–6 times (median = 3) during their pregnancy. Each visit included anatomical and diffusion-weighted MRI, and assessments of waking salivary hormones, hair hormones, and inflammatory cytokines. Reductions in gray matter volume were found by gestational week. Neurite Density Index (NDI), a proxy of axon density, in white matter tracts increased across pregnancy, especially in tracts linked to sensorimotor processing. Progesterone levels were associated with reductions in brain volumetric measurements, and both progesterone and estradiol levels were linked to increases in NDI in white matter tracts. This study highlights the profound neurobiological changes experienced by pregnant individuals and provides insight on neuroplasticity in adulthood.