Study design

This analysis is part of a larger prospective observational study to assess the determinants of GWG in pregnant women with obesity (clinicaltrials.gov: {"type":"clinical-trial","attrs":{"text":"NCT01954342","term_id":"NCT01954342"}}NCT01954342). Energy metabolism including energy expenditure in sedentary and free-living conditions, substrate oxidation, physical activity and endocrine mediators of energy metabolism were measured between 13 and 16 weeks of gestation in 72 pregnant women at Pennington Biomedical Research Center (Baton Rouge, LA, USA). The study was approved by the Pennington Biomedical Research Center Institutional Review Board, and all participants provided written informed consent prior to participation.

Participants and Recruitment: Seventy-two women aged 18 to 40 years, with obesity (BMI ≥30 kg/m²) at screening (<15 weeks of gestation), and a confirmed singleton, viable pregnancy were enrolled. Women were excluded for recent history of smoking, alcohol or drug use, pre-existing hypertension (i.e. systolic blood pressure>160mmHg and diastolic blood pressure>110mmHg), diabetes (HbA1c≥6.5%), HIV or AIDS, severe anemia (hemoglobin<8g/dL and/or hematocrit<24%), contraindications to MRI (implanted metal objects, claustrophobia), prior or planned (within 1 year of expected delivery) bariatric surgery, psychological or eating disorders. Furthermore, women using contraindicated medications or supplements that influence energy intake or expenditure, planned to move out of the study area within the next 2 years or planned to be out of the study area for more than 4 weeks in the next 12 months, planned termination, or were unwilling to avoid pregnancy for 12 months following delivery were excluded. Study participants were recruited from January 2015 to January 2017 through community and social media advertisements and referrals by local obstetricians as previously described (9).