A cohort profile describing the study sample, research objectives and attrition

has been documented by Richter et al. [16]. An adolescent’s ethnic classification was defined by the race classification currently used in South Africa for demographic and restitution purposes. The South African government currently classifies race into black (B; ethnic Africans), white (W; Europeans, Jews and Middle Easterners), coloured or mixed ancestry (MA; mixed race) and Indian (South Asian), and only adolescents whose parents were classified as being of the same ethnic group were included. Data from 1,389 adolescent–biological mother pairs were analysed for this study. The ethnic LY333531 breakdown of the study sample was predominantly B (1,170 (84.2 %)), with the remainder selleck compound of the cohort being made up of W (91 (6.6 %)) and MA (128 (9.2 %)). Indian adolescents and their mothers were excluded as the number of participants was too few to make meaningful comparisons. Children who had chronic diseases such as rheumatoid arthritis, epilepsy and asthma were excluded from the data analyses, as the use of certain medications and immobility are associated risk factors for low bone mass and may increase the incidence of fractures. All subjects provided assent and their parents/guardian INK1197 order provided written, informed

consent. Ethical approval for the study was obtained from the University of the Witwatersrand Committee for Research on Human Subjects. Fracture questionnaire A fracture questionnaire was completed by each adolescent with the assistance of his/her parent or caregiver at 15 and 17/18 years of age. The questionnaire at age 15 included information on previous fractures from birth until 15 years of age, including site of fracture with the aid of a skeletal diagram, and the causes and age at fracture. At age 17/18, the fracture questionnaire included information on fractures that had occurred since their previous questionnaire.

Mothers/caregivers also completed a questionnaire on fractures occurring since birth in the adolescent’s sibling(s). Biological mothers completed questionnaires on their own fractures prior to the age of 18 years. Due to the retrospective nature of the fracture data collection, the fractures could not be verified by radiographs. Anthropometric Inositol monophosphatase 1 measurements and dual-energy X-ray absorptiometer-derived parameters Anthropometric measurements and bone mass data on the subjects at the age of 17/18 years were used for this study. Biological mothers’ anthropometric data and bone mass measurements had been collected over 2 years when the adolescents were approximately 13 years of age. Height was measured to the nearest millimetre using a stadiometer (Holtain, Crosswell, UK). Weight was measured to the last 100 g using a digital scale (Dismed, Halfway House, South Africa), with participants wearing light clothing and no shoes.