The association of socio-economic position across the life course and age at menopause: the British Women's Heart and Health Study.

OBJECTIVE: To assess the association of indicators of adverse socio-economic position from across the life course with age at menopause.
DESIGN: Cross sectional study as part of the British Women's Heart and Health Study.
SETTING: 23 British towns. POPULATION: Three thousand and five hundred and thirteen women aged 60-79 years from a total cohort of 4286. Women who underwent a hysterectomy or oophorectomy prior to their 'natural' menopause or who were taking hormone replacement therapy around the perimenopausal period and for whom a biological age at menopause could not be calculated were excluded from this study. MAIN OUTCOME MEASURES: Age at menopause.
RESULTS: Most of the 10 indicators of adverse socio-economic position from childhood through to adulthood were linearly associated with a younger age at menopause. In age adjusted analyses, women from manual social classes in childhood began their menopause on average 0.68 years (95% confidence interval [CI] 0.11, 1.3) earlier than those from non-manual social classes. Those who lived in a house as a child without a bathroom began their menopause 0.47 years (95% CI 0.12, 0.82) earlier than those with a bathroom. Those who shared a bedroom began 0.36 years (95% CI 0.03, 0.70) earlier than those who had their own bedroom and finally those who lived in a household with no access to a car as a child began their menopause 0.47 years (95% CI 0.02, 0.95) earlier than those with access to a car. Adult indicators of adverse socio-economic position were similarly associated with earlier age at menopause. Age at completing full time education was not substantively associated with age at menopause. The inverse associations between each of the indicators of both childhood and adult socio-economic position and age at menopause were not importantly affected by adjustment for other reproductive factors but they attenuated by between 6% and 21% with adjustment for adult smoking and body mass index. The inverse associations between each of the childhood indicators of socio-economic position only and age at menopause attenuated markedly (between 12% and 70%) with adjustment for adult leg length. There was a cumulative effect of disadvantage across the life course demonstrated by a strong linear trend between a composite score of the 10 socio-economic indicators and young age at menopause. The age at onset of menopause for women who had 9 or 10 adverse socio-economic indicators was on average 1.70 years (95% CI 0.36, 3.0) younger than that of women with none or only one indicator.
CONCLUSIONS: Adverse socio-economic circumstances in childhood, as well as in adulthood, are associated with an earlier age at menopause. The association between childhood deprivation and early menopause may at least in part be mediated via exposures, such as childhood diet, which affect both linear growth and age at menopause.