Baby brain? It may shrink during pregnancy, but have better connectivity

Embargoed until: Publicly released: 2024-09-17 01:00

International

Major white matter tracts demonstrated increasing microstructural integrity over pregnancy. Credit: Daniela Cossio

Regions of the human brain may shrink in size during pregnancy, but have better connectivity, with only a few regions of the brain remaining unchanged by the transition to motherhood, according to US researchers. The findings, based on brain scans of one mother, represent one of the first comprehensive maps of brain changes before, during and after human pregnancy, they say. They conducted 26 MRI scans and blood evaluations of the 38-year-old woman, from three weeks pre-conception, through the three trimesters of pregnancy, to two years after giving birth, when the testing period ended, and compared them with scans from eight non-pregnant women. They found widespread decreases in cortical volume and thickness by the ninth week of pregnancy, particularly in regions such as the default mode network, which is linked with social cognition. They also observed increases in white matter microstructure, ventricular volume and cerebrospinal fluid. These changes were linked with rising oestradiol and progesterone hormone levels, with some persisting after birth. Some of these changes were still present at two years after giving birth, including reduced cortical volume and thickness, whilst others returned to similar levels as pre-conception by around two months after the birth, the experts say. As the findings are based on a single woman, further research should investigate whether the same is true in larger groups, the researchers conclude.

Media release

From: Springer Nature

Investigating pregnancy-related brain changes

Regions of the human brain may shrink in size during pregnancy, but have better connectivity, with only a few regions of the brain remaining untouched by the transition to motherhood, according to research published in Nature Neuroscience. The findings, based on brain scans from one mother, may represent one of the first comprehensive maps of neuroanatomical changes before, during and after human pregnancy.

Nearly 85% of women become pregnant at least once during their lifetime, and 140 million women each year become pregnant. Pregnancy is known to cause physiological changes to the body, but the corresponding neural changes are not well understood.

Laura Pritschet and colleagues analysed the pregnancy-related brain changes of a healthy 38-year-old woman. They conducted 26 MRI scans and blood evaluations from 3 weeks pre-conception (4 scans) through the 3 trimesters of pregnancy, (15 scans) to 2 years postpartum (7 scans), when the testing period ended. These scans were compared to brain changes observed in 8 control individuals. The authors found widespread decreases in cortical volume and thickness by the ninth week of pregnancy, particularly in regions such as the default mode network, which is associated with social cognition. They also observed increases in white matter microstructure, ventricular volume and cerebrospinal fluid. These changes were associated with rising estradiol and progesterone hormone levels, with some persisting after birth. Some of these changes persisted at two years postpartum, including reduced cortical volume and thickness, whilst others returned to similar levels as preconception by around two months after the birth.

Although further research is needed to investigate the longer-term impacts of pregnancy on the brain, and the consistency of these brain changes across a broader population, the findings improve our understanding of the neural changes associated with pregnancy. There are also potential implications for perinatal mental health (such as neurological effects tied to pre-eclampsia or oedema), parenting behaviours and brain aging, the authors suggest.

Please note that an online press briefing for the paper below will take place UNDER STRICT EMBARGO on Thursday 12th September at 3pm London time (BST) / 10am US Eastern Time.

Authors Elizabeth Chrastil and Emily Jacobs will discuss the research. This will be followed by a Q&A session.

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Multimedia

Cortical gray matter volume change

Neuroanatomical changes unfolding throughout gestation

Major white matter tracts

A woman underwent brain imaging from preconception through two years postpartum

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Research Springer Nature, Web page The URL will go live after the embargo ends

Journal/
conference: Nature Neuroscience

Research:Paper

Organisation/s: University of California, USA

Funder: This study was supported by the Ann S. Bowers Women’s Brain Health Initiative (to E.G.J. and C.T.), UC Irvine Campus Funds (to E.R.C.), UC Academic Senate (to E.G.J.), ReproGrants (to H.G., E.G.J. and E.R.C.), NIH F99AG07979 (to L.P.), NIH T32 AG00096-40 (to D.C.), NIH AG063843 (to E.G.J.) and NIH ZIAMH002783 (to J.F. and D.A.H.).

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