Adults conceived during colder months may exhibit higher brown adipose tissue activity and energy expenditure compared with those conceived in warmer months, according to a recent study.
Published in Nature Metabolism, researchers examined whether environmental temperature affected brown adipose tissue (BAT) activity and energy homeostasis in human offspring.
Five independent cohorts of healthy Japanese adults were analyzed, assessing BAT activity using fluorine-18–fluorodeoxyglucose PET–computed tomography, near-infrared time-resolved spectroscopy, and doubly labeled water. These methods quantified cold-induced thermogenesis, diet-induced thermogenesis, and total energy expenditure (EE), noted Takeshi Yoneshiro, of Tohoku University Graduate School of Medicine in Sendai, Japan.
In cohort 1 (n = 356 young male participants), cold-induced BAT activity was significantly greater among those conceived during colder months compared with those conceived during warmer months (78.2% vs 66%). This association remained significant after adjusting for age and body mass index and was observed across multiple BAT depots. Notably, season of birth was not associated with BAT activity.
Cohort 2 (n = 286, mixed ages and sexes) replicated the findings using supraclavicular BAT density measured via total hemoglobin, revealing greater prevalence of dense BAT in participants conceived during cold seasons (56.4% vs 44.4%).
In a crossover design, the researchers assessed thermogenesis in cohort 3 (n = 42) using indirect calorimetry and found that cold-induced thermogenesis measured in winter was higher among participants conceived during cold seasons, whereas resting EE under thermoneutral conditions did not differ between the groups.
Cohort 4 (n = 23) demonstrated higher postprandial diet-induced thermogenesis in the cold-conception group, further supporting enhanced thermogenic capacity. In cohort 5 (n = 41), total EE under free-living conditions, adjusted for fat-free mass and physical activity, was higher among participants conceived during colder months.
Structural equation modeling using data from cohorts 1 and 2 indicated that season of conception indirectly influenced adult BMI through BAT activation, without evidence of a direct effect on BMI.
Meteorologic data from 93 participants showed that lower outdoor temperatures and greater diurnal temperature variation at the estimated time of conception were associated with increased likelihood of BAT activity in adulthood (adjusted odds ratio for diurnal variation = 1.61), while no associations were observed for temperatures during gestation.
The researchers reported no relevant financial disclosures.
