Minipuberty of Infancy and the Timing of Pubertal Development in Adolescence: a Follow-up of the Infant Feeding and Early Development (IFED) Cohort

Background: Earlier puberty is associated with adverse health throughout a person s life. The average age when puberty begins has been declining over the past decades in girls, and may also be declining in boys. The reasons for this shift are unknown. Objective: To determine whether internal (physical, hormonal) or external (feeding, environment) factors during infancy affect growth and the timing of puberty. Eligibility: Mothers (or other parent/guardian) and their children who completed the Infant Feeding and Early Development (IFED) study. Design: Participants will complete all activities at home for this natural history study. Participant mothers will fill out two 15-minute questionnaires: * One will be about themselves. They will answer questions about their body size in childhood, their puberty, and their pregnancies. * The other will be about their child. They will answer questions about their child s puberty and lifestyle. Child participants will fill out a questionnaire about their body changes during puberty. This will take 10 minutes. Participants will be sent an electronic scale and a measuring tape. They will measure the child s weight, height, and waist and hip circumference. These numbers can be submitted online or by phone or mail. Participants will receive a kit for collecting urine samples. Child participants will collect urine in a cup upon waking 4 days in a row. A special filter card is dipped in the cup then hung to dry. The dried cards will be mailed back. Participants will allow researchers to access their child s medical records. Questionnaires and body measurements will be repeated after 6 and 12 months. Urine sample collection will be repeated after 12 months. All questionnaires can be done either online, by mail, or by phone on request.