Postnatal Exercise to Activate Baby's Brown Fat (PEABaBy)

Impact of Acute Exercise and Habitual Physical Activity on Human Milk Composition and Childhood Obesity Risk

The purpose of this study is to learn how exercise and physical activity during pregnancy and after pregnancy may affect the composition of breastmilk. Certain changes in breast milk after exercise may have an impact on how infants use energy. Understanding this process may improve public health recommendations for exercise during and after pregnancy. This study can help investigators learn more about how maternal exercise patterns may affect body growth and obesity risk in infants who are breastfed. This research may help identify how different factors can influence healthy weight and early development in infants.

Study Overview

• Status: Recruiting
• Conditions: Physical Activity; Pregnancy; Exercise; Childhood Obesity; Lactation; Breastfeeding; Childhood Obesity Prevention
• Intervention / Treatment: Behavioral: Active group

Detailed Description

Epidemiological studies suggest that breastfeeding protects against risk of obesity, diabetes, asthma, and other childhood diseases. However, the specific compounds within breastmilk that are responsible for its protective effects are not fully understood. Moreover, prior work from this investigative team has shown that human milk composition varies substantially between individuals according to factors such as body mass index (BMI), diabetes status, diet, and physical activity. Gaining a better understanding of how modifiable risk factors may impact human milk composition would have the potential to identify strategies to enhance the health-promoting benefits of human milk.

In this project, the investigators will study the impact of maternal exercise on human milk composition. The central hypothesis is that maternal exercise induces changes in breast milk metabolites and lipids that result in activation of infant brown fat, increased infant energy expenditure, and reduced obesity risk.

The study will include assessments of habitual activity during pregnancy and the postpartum period, supervised bouts acute moderate exercise, as well as analysis of human milk composition, infant growth and body composition, and infant energy expenditure.

• Study Type: Interventional
• Enrollment (Estimated): 200
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Elvira M Isganaitis, MD, MPH; Phone Number: 617-309-4554; Email: elvira.isganaitis@joslin.harvard.edu
• Study Contact Backup: Name: Study Coordinator; Phone Number: 857-289-3455; Email: PeaBaBy@joslin.harvard.edu

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02215
      • Recruiting
      • Joslin Diabetes Center
      • Contact: Elvira Isganaitis, MD; Email: elvira.isganaitis@joslin.harvard.edu
  • Oklahoma
    • Oklahoma City, Oklahoma, United States, 73104
      • Recruiting
      • Oklahoma University College of Medicine
      • Contact: Katy Duncan; Email: katy-duncan@ou.edu
      • Principal Investigator: David Fields, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 18-45 y of age at the time of enrollment
• Pre-gravid or first trimester BMI 18.5 -40 kg/m2
• Uncomplicated singleton pregnancy
• Intention to exclusively breastfeed for >3 months and, if parity >1, that they successfully breastfed a previous pregnancy
• Term pregnancy (gestational age 37 to <42 weeks)
• Infant with birth weight >10th percentile of weight for gestational age

Exclusion Criteria:

• Any obstetric contra-indication to exercise at 1 month
• Diagnosis of uncontrolled (HbA1c >7%) type 1 or type 2 diabetes, or gestational diabetes managed with insulin
• Intrauterine growth restriction
• Pre-eclampsia or other pregnancy complications
• Alcohol, cannabis or tobacco use
• Known congenital metabolic, endocrine disease, or congenital illness affecting infant feeding/growth
• Major fetal anomalies
• Musculoskeletal issues that would make exercise difficult

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Control group; Usual care
Experimental: Enhanced physical activity; Participants in this group will be encouraged to engage in daily physical activity	Behavioral: Active group; For participants randomized to the Active group, there will be weekly phone calls with study staff during which step counts and exercise bouts from the previous week will be reviewed, and exercise goals for the following week will be gradually increased.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Altered breast milk lipidome	Milk composition measured through lipidomics	8 weeks
Altered breast milk metabolome	Human milk composition measured via metabolomics	8 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Infant body composition	Infant body composition will be measured using air-displacement plethysmography (ADP; i.e., PeaPod) at 1 and 3-mo and by DXA at 6 and 12-mo: percentage fat, total fat mass.	3 months, 6 months, and 12 months
Infant body mass index (BMI)	Body mass index (BMI) z-score for age and sex, usual range [-4,4]; lower BMI z-score represents lower adiposity	3 months, 6 months, and 12 months
Infant resting metabolic rate	Infant Resting Metabolic Rate	3 months of age

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Infant brown adipose tissue anatomy	MRI measurement of brown adipose tissue (BAT) volume and distribution	2 months
Heat production	Infant Infrared Thermography to measure brown adipose tissue activity	1 month and 3 months

Collaborators and Investigators

• Sponsor: Joslin Diabetes Center
• Collaborators: University of Oklahoma; National Institutes of Health (NIH)

Study record dates

Study Major Dates

• Study Start (Actual): December 1, 2025
• Primary Completion (Estimated): July 1, 2030
• Study Completion (Estimated): July 1, 2030

Study Registration Dates

• First Submitted: February 17, 2026
• First Submitted That Met QC Criteria: March 11, 2026
• First Posted (Actual): March 12, 2026

Study Record Updates

• Last Update Posted (Actual): March 12, 2026
• Last Update Submitted That Met QC Criteria: March 11, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Exercise; Pregnancy; Lactation; Breastfeeding; Breast milk
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Overweight; Obesity; Pathological Conditions, Signs and Symptoms; Behavior; Nutritional and Metabolic Diseases; Signs and Symptoms; Feeding Behavior; Pediatric Obesity; Motor Activity; Breast Feeding
• Other Study ID Numbers: STUDY00000313; R01HD117197 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No