Early menopause affects 1 in 14 women aged 30 to 49 living in low and middle income countries, finds a pooled data analysis of its prevalence in 44 nations published in the open access journal BMJ Global Health.
The incidence is consistently higher in rural areas than it is in urban areas across all regions and countries included in the analysis, but education and delayed childbearing strongly minimise the risk.
Women usually go through the menopause between the ages of 45 and 55, but it is considered to be early if it occurs before the age of 45, and premature if it occurs before the age of 40, note the researchers.
Early and premature menopause are major public health concerns, because they heighten the risks of cardiovascular disease, osteoporosis, metabolic disorders, cognitive decline, depression, and early death, as well as seriously affecting the quality of life, they add.
To date, research findings on the prevalence of early and premature menopause have been fragmented, focused on individual countries, and missing a detailed look at individual-level sociodemographic and reproductive factors, explain the researchers.
To close this important information gap, they drew on pooled data from the Demographic and Health Survey (DHS) for 716,648 women between the ages of 30 and 49 in 44 low and middle income countries, where menopause tends to occur earlier than it does in high income countries.
All regions of the world were included other than North and South America for which no data were available.
The researchers focused on the potentially explanatory variables of: health factors, such as age at first marriage and first birth; number of live births; terminations; community level factors, such as place of residence; and individual-level characteristics, such as age, education, occupation, wealth index and exposure to media.
The data revealed that most survey respondents were between 30 and 34 (29%),while both women and their husbands were most often educated up to secondary school level (34% and 17%, respectively). Most respondents lived in rural areas (62%).
More than a third (38%) of women married before the age of 18, and around 1 in 5 (21%) gave birth to their first child before this age. Over half the women (58%) had 3 or more children.
The overall prevalence of premature or early menopause was just over 7% (51,000 out of 716,648 women), which is much higher than previous global estimates, say the researchers, with the highest prevalence among 40-44 year olds (14%).
There was a six-fold difference between those countries with the highest and lowest prevalence, the analysis showed.
The highest prevalence was in Ethiopia, Indonesia, and Myanmar: 12%;11.5%; and just over 10%, respectively. The lowest prevalence was in Jordan, Gabon, and Armenia: just over 2%; nearly 3%; and nearly 3%, respectively.
Certain factors were associated with a high prevalence. These included giving birth before the age of 18 (11%); marriage before the age of 18 (just over 10%); no formal education (just over 9%); material disadvantage (just over 8%); no exposure to media (just over 8%); residence in rural areas (8%); and 3 or more children (7.5%).
The disparity in prevalence between rural and urban areas was consistent across all countries and regions, the analysis showed.
This "reflects fundamental inequalities in healthcare access, nutritional status, educational opportunities and occupational exposures," highlight the researchers, adding that women in these areas are more likely to work as manual labourers and face workplace hazards, including exposure to agricultural chemicals.
Education was protective, with progressively lower odds the higher the level of education. Compared with women with no formal education, those with a college education were 58% less likely to experience an early or premature menopause. And women who were employed were 14% less likely to do so than women who weren't working.
This is an observational study, and as such, no firm conclusions can be drawn about cause and effect. And the researchers acknowledge that their study relied on self-reported data and that they weren't able to distinguish between natural and surgically induced menopause.
Several potentially important factors associated with menopause aren't consistently included in the DHS survey data either, they note: smoking; alcohol intake; physical activity; diet; long term conditions; hormonal contraceptive use and breastfeeding duration; and environmental exposures.
But the health consequences of early and premature menopause will strain the health systems of low and middle income countries, particularly in South and East Asia and Pacific, and sub-Saharan Africa, point out the researchers.
"With populations in [these countries] ageing rapidly and women expected to spend an increasing proportion of their lives in the postmenopausal state, the prevalence represents a substantial and growing burden on health systems already constrained by competing priorities and limited resources," they write.
The findings "underscore the urgent need to integrate menopause into reproductive health and non-communicable disease programmes, particularly targeting rural areas and addressing social determinants, including girls' education and delayed marriage," they conclude.
