OBJECTIVE: To explore relationships between body mass index (BMI, kg/m2) and ... populations in developed countries became heavier, ..... Never smoked.
International Journal of Obesity (2000) 24, 1360±1368 ß 2000 Macmillan Publishers Ltd All rights reserved 0307±0565/00 $15.00 www.nature.com/ijo
Relationships between body mass index and well-being in young Australian women WJ Brown1*, G Mishra2, J Kenardy3 and A Dobson4 1
School of Human Movement Studies, University of Queensland, Brisbane, Australia; 2Research Institute for Gender and Health, University of Newcastle, Newcastle, Australia; 3School of Psychology, University of Queensland, Brisbane, Australia; and 4School of Population Health, University of Queensland, Brisbane, Australia
OBJECTIVE: To explore relationships between body mass index (BMI, kg=m2) and indicators of health and well-being in young Australian women. DESIGN: Population based cohort study Ð baseline cross sectional data. SUBJECTS: 14,779 women aged 18 ± 23 who participated in the baseline survey of the Australian Longitudinal Study on Women's Health in 1996. MEASUREMENTS: Self-reported height, weight, medical conditions, symptoms and SF-36. RESULTS: The majority of women (68%) had a BMI in the range 18.5 ± 30 were included in the BMI 30 category. (Each line in Figure 1 therefore represents the ®tted curve for about 13,000 data points, but with variations in the exact numbers due to missing data for some items.) BMI was then categorized according to the recommendation of the WHO7 as: 30 kg=m2 are included in the BMI category labeled 30. International Journal of Obesity
Healthy weight for young women WJ Brown et al
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The associations between BMI (expressed as a continuous variable) and prevalence of speci®c medical problems (hypertension, low iron level, and asthma), symptoms (headaches=migraine, back pain, irregular monthly periods and dif®culty in sleeping) and high use of GP services (de®ned as more than ®ve consultations per year), are shown in Figure 1. The prevalence of hypertension increased consistently as BMI increased above a level of about 20 kg=m2. The curves for asthma, headaches, back pain, irregular periods, dif®culty sleeping and GP visits showed `J' shaped curves, with the lowest prevalences occurring around BMI 20 ± 22 kg=m2. In contrast the prevalence of low iron decreased with increasing BMI (see Figure 1). The proportion of women in each BMI category, and the distribution of socio-demographic variables across the BMI categories are shown in Table 2. Women from remote areas, those with no job and those who had given birth at least once were overrepresented in the highest BMI categories (25 kg=m2). In contrast, there was greater representation of smokers in the two lowest BMI categories.
While the relationship between prevalence of miscarriage among women who reported having been pregnant at least once, and BMI category, was not statistically signi®cant, a noteworthy trend was evident. The rate of miscarriage among women in the lowest BMI category was 35% compared with 22% across the other categories (Fisher's exact test for difference, P 0.014). The adjusted odds ratios for each of the variables shown in Figure 1, for the six BMI categories, are shown in Table 3. Relative to the reference category of BMI between 20 and 25, the prevalence of hypertension, asthma, headaches or migraines, and ®ve or more GP visits increased progressively in each BMI category greater than 25 (Table 3). Women with BMI 30 were also more likely to report back pain, irregular periods and dif®culty in sleeping. The only symptom which was signi®cantly associated with low BMI was irregular periods, which was more commonly reported by women with BMI
