Patient description: A 16-year-old girl came to the clinic complaining of weight gain and abnormal menstrual cycles. Her BMI was 24, but she has gained 5 kg in the past few weeks. She gets tired more frequently and does not have energy to go dancing with her friends. Her lab results were remarkable for high TSH levels (15 mU/L) and low free T4 levels (0.18 ng/dl). Her anti-TPO levels were extremely high (136 IU/ml). She was diagnosed with Hashimoto disease. She does not smoke and she is not sexually active.

Clinical trial eligibility criteria: eligible ages (years): 18.0-40.0,  Overweight and Obesity Physical Activity Weight Change, Body Eating Behavior Pregnant women Overweight or obese [body mass index range 24 >40 (if BMI (kg/m^2) is > 40, consultation with woman's health care provider (PCP/OBGYN) will be made to determine and ensure she does not have any contraindications to exercise) PI Danielle Downs will have communication with Dr. Hovick from MNPG to give information on the woman. The investigators also have a physician consent form (see Physician Patient Consent to Participate in documents) that the physician will complete as to whether the woman is eligible or not eligible to participate Normal weight women with a BMI range of 18.0 to 23.9 can be enrolled in to the study as control participants (same measures of data collection, no opportunity for intervention) Ages 18-40 years [based on pilot data this group comprises >85% of the live births in Central Pennsylvania] t, 2nd or 3rd pregnancy 6-16 weeks gestation Able to read, understand, and speak English Residing in and around State College, PA t and 2nd time pregnant mothers [none or one other live or still born, biological children > 25 weeks gestation prior to this pregnancy; it may be conceivable that a woman has a blended family due to a mixed marriage and she will not be excluded if she is a parent to a guardian, foster child, or step child] Access to a computer or willingness to come onsite to complete study materials  Having more than one live or stillborn child > 25 weeks gestation; late-term pregnancy loss Diabetes at study entry [while future adaptations of this study will target women with diabetes, for the pilot study, they will be excluded to control for this confound] Contraindications to exercise in pregnancy [Hemodynamically significant heart disease, Restrictive lung disease, Incompetent cervix/cerclage, Persistent second [or third] trimester bleeding, Placenta previa after 26 weeks of gestation, Premature labor during the current pregnancy, Ruptured membranes, Preeclampsia/pregnancy-induced hypertension] per the ACOG guidelines [ACOG Committee on Obstetric Practice. [(2015, December). ACOG Committee opinion. Number 650: Physical Activity and Exercise During Pregnancy and the Postpartum Period. Obstetrics and Gynecology, 126,(6), 135-142] Having a body mass index less than 18 or over 40 (exclusion only if physician doesn't provide consent for BMI is over 40) Not planning to live in the area for the study duration Severe allergies or dietary restrictions that would preclude eating healthy foods Not able to read, understand, and/or speak English Cognitively impaired Currently smoking Infants not born to participants