An Examination of Brown Adipose Tissue and Energy Expenditure in Infants

Study Overview
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Brief Summary
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Excess fetal adipose tissue growth during intrauterine development increases future obesity risk. Development of brown adipose tissue, a highly thermogenic organ in utero, may affect postnatal energy expenditure, thus influencing obesity risk. This research study is designed to understand the developmental origins of energy balance by examining maternal and neonatal factors that influence neonatal brown adipose tissue and to quantify its physiological relevance to energy expenditure in human neonates.

Detailed Description
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The developmental origins of obesity begin in utero with growth and differentiation of adipose tissue. Fetal white adipose tissue accretion is highly variable and dependent on the maternal intrauterine environment. Unlike white adipose tissue, brown adipose tissue has a high capacity for thermogenesis. Brown adipose tissue is present at birth and it is believed to support the critical function of thermoregulation in early postnatal life. Therefore, Brown adipose tissue may also influence the development of neonatal energy balance. Similar to white adipose tissue, it is hypothesized that development of Brown adipose tissue in utero is also influenced by maternal factors such as prepregnancy body mass index and gestational weight gain. The research aims of this study to 1) identify maternal and neonatal factors that contribute to neonatal Brown adipose tissue and 2) to identify changes in neonatal Brown adipose tissue and to energy expenditure in response to a mild cold exposure. To achieve these aims, we will conduct a cross-sectional, observational study in up to 60 infants 0-3 weeks of age. Using state-of-the-art methodology, we will assess brown adipose tissue, body composition, and resting metabolic rate under thermoneutral and mild-cold stimulated conditions.

Official Title
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An Examination of Brown Adipose Tissue and Energy Expenditure in Infants

Conditions
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Brown Adipose Tissue

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: aged 0 weeks to less than 3 weeks at visit 1 be willing to complete MRI procedures Exclusion Criteria: Unable to complete two clinic visits within 14 days Born with health conditions that would render the procedures unsafe Born earlier than 36 and 0 days gestation Taken a steroid drug since birth Implanted metal or electronic objects that render MRI unsafe

Ages Eligible for Study
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Maximum Age: 5 Weeks

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Brown Adipose Tissue Fat-signal Fraction Difference Between Thermoneutral and Mild-Cold Environment | The difference in the infants' fat-signal fraction (ratio of lipid to water, expressed as a percentage), assessed by Magnetic Resonance Imaging, between a thermoneutral environment and a mild-cold exposure. | 14 days | 
| Energy Expenditure Difference Between Thermoneutral and Mild-Cold Environment | The difference in the infants' energy expenditure (expressed as kilocalories per day), assessed by room calorimetry, between a thermoneutral environment and a mild-cold exposure. | 14 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Brown Adipose Tissue Volume Difference Between Mothers Enrolled in Prenatal Intervention | In an ancillary aim of the study, we will examine the difference in the infants' brown adipose tissue volume (expressed as cubic centimeters), assessed by Magnetic Resonance Imaging, between infants born to mothers enrolled in a prenatal weight maintenance intervention (R01DK124806) and infants born to mothers seeking routine prenatal care. | 1 day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Infant, Energy Expenditure, Indirect Calorimetry, Brown Fat, Neonatal, Magnetic Resonance Imaging