Srishti Sadhir

SRISHITI SADHIR, then a graduate student at Duke University, Durham, North Carolina, was approved funding in September 2023 to aid research on “Maternal Energetic Strategies During Pregnancy,” supervised by Dr. Herman Pontzer. This study explored how pregnant individuals manage the high energy demands of pregnancy, especially considering variation in physical activity. In particular, does the body have a natural limit on how much energy it can use or absorb during pregnancy (~2.5 times basal metabolic rate), and does this limit affect gestational weight gain or fetal growth? To address this research question, 50 pregnant participants (30 athletes and 20 non-athletes) were followed over their pregnancies. Total daily energy expenditure, physical activity, body composition, and birth outcomes were measured using the doubly labeled water method, accelerometry, fitness trackers, bioelectrical impedance scales, and self-reported data. Results demonstrated that no participant expended more energy than the expected limit, even among the most active participants. Although athletes had substantially higher levels of physical activity during pregnancy, their overall energy use was similar to non-athletes. The body seemed to adjust by reducing fat mass gain and shifting energy allocation, especially in later pregnancy. Importantly, babies were not affected by how much energy their mothers used, suggesting the body protects fetal development, even when energy is limited. This research offers insights into the evolution of unique human birth characteristics and ways to support healthy pregnancies across diverse lifestyles.