MRI-based structural development of the human newborn hypothalamus.

Area of Science:

• Neuroscience
• Developmental Biology
• Radiology

Background:

• Intrauterine exposures may affect early brain development and future health risks.
• The hypothalamus regulates crucial early life functions like sleep, growth, and metabolism.
• Limited human data exist on early hypothalamic structural development and its influencing factors.

Purpose of the Study:

• To characterize normative hypothalamic volume development in newborns.
• To investigate the impact of intrauterine exposures, specifically gestational age and maternal smoking, on hypothalamic volume.
• To assess the persistence of these associations into adolescence.

Main Methods:

• Utilized T1-weighted MRI scans from the Developing Human Connectome Project (dHCP) for 631 newborns.
• Analyzed associations between hypothalamic volume and postmenstrual age (PMA), sex, and gestational age (GA).
• Examined the effect of maternal cigarette smoking during pregnancy and validated findings in an adolescent cohort (ABCD study).

Main Results:

• Hypothalamus volume increased with PMA but not when adjusted for total brain volume.
• Males had larger absolute but smaller relative hypothalamic volumes.
• Lower gestational age (GA) was associated with larger relative hypothalamic volume, moderated by sex.
• Maternal smoking during pregnancy was linked to smaller newborn hypothalamus volume, showing dose dependence.
• These smoking-related differences persisted into adolescence.

Conclusions:

• Early-life hypothalamic volume development is influenced by normative growth and intrauterine exposures.
• Maternal smoking during pregnancy is a significant factor associated with reduced hypothalamus volume, with lasting effects into adolescence.
• These findings highlight the hypothalamus's vulnerability to prenatal environment and its implications for long-term health.