Country of birth, country of residence, and menopausal transitions and symptoms: British birth cohort and Australian Longitudinal Study on Women's Health

Objective: To explore endocrine-related and general symptoms among three groups of middle-aged women defined by country of birth and country of residence, in the context of debates about biological, cultural and other factors in menopause. Methods: British-born women participating in a British birth cohort study (n=1,362) and age-matched Australian-born (n=1,724) and British-born (n=233) Australian women selected from the Australian Longitudinal Study on Women's Health (ALSWH) responded to two waves of surveys at ages 48 and 50. Results: Australian-Australian and British-Australian women report reaching menopause later than British-British women, even after accounting for smoking status and parity. Hormone replacement therapy (HRT) use was lower and hysterectomy was more common among both Australian groups, probably reflecting differences in health services between Britain and Australia. The Australian-Australian and British-Australian groups were more likely to report endocrine-related symptoms than the British-British group, even after adjusting for menopausal status. British-British women were more likely to report some general symptoms. Conclusions: Symptom reporting is high among Australian and British midlife women and varies by country of residence, country of birth and menopausal status. Implications: The data do not support either a simple cultural or a simple biological explanation for differences in menopause experience.

Identifying the energy gap: Magnitude and determinants of 5-year weight gain in midage women

Objective: The aims of this study were to estimate average yearly weight gain in midage women and to identify the determinants of weight gain and gaining weight at double the average rate. Research Methods and Procedures: The study sample comprised 8071 participants (45 to 55 years old) in the Australian Longitudinal Study on Women's Health who completed mailed surveys in 1996, 1998, and 2001. Results: On average, the women gained almost 0.5 kg per year [average 2.42 kg (95% confidence interval, 2.29 to 2.54) over 5 years]. In multivariate analyses, variables associated with energy balance (physical activity, sitting time, and energy intake), as well as quitting smoking, menopause/hysterectomy, and baseline BMI category were significantly associated with weight gain, but other behavioral and demographic characteristics were not. After adjustment for all of the other biological and behavioral variables, the odds of gaining weight at about twice the average rate (> 5 kg over 5 years) were highest for women who quit smoking (odds ratio = 2.94; 95% confidence interval, 2.17, 3.96). There were also independent relationships between the odds of gaining > 5 kg and lower levels of habitual physical activity, more time spent sitting, energy intake (but only in women with BMI > 25 at baseline), menopause transition, and hysterectomy. Discussion: The average weight gain equates with an energy imbalance of only about 10 kcal or 40 kJ per day, which suggests that small sustained changes in the modifiable behavioral variables could prevent further weight gain.

Birth weight and age at menopause in Australian female twin pairs: exploration of the fetal origin hypothesis

In a twin sample where duration of gestation can be controlled, a specific example of the fetal origins hypothesis concerning association between low birth weight and early age at menopause is explored. The hypothesis is based on the physiologically plausible path from intrauterine growth retardation and reduced numbers of primary follicles to an earlier menopause. The sample comprised 323 Australian female twin pairs where both co-twins had reached menopause naturally and reported on their weight at birth. Regression analysis showed no linear association between the two variables (P = 0.371, r(2) = 0.0009). Intra-pair differences in age at menopause were investigated in the context of relative birth weight of co-twins. In 265 pairs an intra-pair birth a eight difference was reported. In monozygotic (MZ) pairs (n = 168) this allowed for control of genetic effects as well as gestation duration. No significant differences dependent on birth weight relative to co-twin were found for age at natural menopause in either MZ or dizygotic (DZ) twin pairs, even in pairs whose birth weights differed markedly. There was some indication that twins with premature ovarian failure were heavier at birth than twins with normal or later menopausal age. We conclude that the hypothesis that lower birth weight is associated with earlier menopause is not supported by our data.