Investigating the Impact of Obesity on Pubertal Development in Girls

Background: Studies suggest that overweight girls may be developing breast tissue, and therefore starting puberty, earlier than normal weight girls. However, it is hard to distinguish breast tissue from fatty tissue. Researchers think that by using breast ultrasound, among other tests, they can do a better job of telling whether an overweight girl has breast tissue. This will help them understand if overweight girls are truly entering puberty before normal weight girls. Objective: To find out if overweight girls go through puberty earlier than normal weight girls. Eligibility: Healthy girls 8-14 years old who: * Are normal weight or overweight * Have some breast development * Have not started their first period Design: Parents of participants will be screened over the phone. Most participants will have 1 visit. However, they can choose to have multiple visits within 4 weeks. The visit will include: * Physical exam that includes examination of the breasts and genital area * Breast ultrasound: A small hand-held device will be passed back and forth over the chest. It uses sound waves to create a picture of the breast tissue. * Pelvic ultrasound: A small, handheld device will be passed back and forth over the lower belly. It uses sound waves to create a picture of the ovaries. * Urine and blood test * A special x-ray called a DXA to measure the amount of fat in the body: The participant will lie still on a table while the x-ray takes pictures of the body. X-ray of the hand: The picture will tell researchers how mature the participant s bones are. Participants may be asked to come back 6 months later to repeat these tests.

Over the past decade, there has been an alarming trend toward earlier breast development in girls. The contemporaneous obesity epidemic has led to speculation that obesity may be driving early puberty. However, questions remain about the validity of reports of early puberty among obese girls due to the difficulty in distinguishing fatty tissue from breast tissue in this population. The physiological basis for early puberty among obese girls is also unknown. The current proposal aims to investigate pubertal development in pre-menarchal obese compared with normal weight girls using more robust methods such as breast morphological staging via ultrasonography and intensive reproductive axis phenotyping. Study procedures include blood draws, DXA (for body composition), hand x-ray (for bone age), breast and transabdominal (pelvic) ultrasounds, and anthropometrics.

* INCLUSION CRITERIA: * Girls without a chronic medical condition * Normal weight (BMI 5th-85th%) or overweight/obese (BMI \> 85th%) * 8-14 years old * Some breast development * Pre-menarchal EXCLUSION CRITERIA: * Treated with medications that may affect reproductive hormones (e.g. birth control pills). * Pregnancy During the study, the PI s discretion may be used to determine final eligibility. The PI s discretion may be used at any point in the study (pre-screening, clinical/lab assessments, etc.) to ensure participants are not subjected to unnecessary procedures or visits.