Use of oral contraceptives and hormone replacement therapy in the WHO MONICA project

To compare menopausal age and the use of oral contraceptives (OC) and hormonal replacement therapy (HRT) between the 32 populations of the WHO MONICA Project, representing 20 different countries.

Using a uniform protocol, age at menopause and the use of OC and HRT was recorded in a random sample of 25-64 year-old women attending the final MONICA population cardiovascular risk factor survey between 1989 and 1997. A total of 39,120 women were included.

There were wide variations between the populations in the use of OC and HRT. The use of OC varied between 0 and 52% in pre-menopausal women aged 35-44 years, Central and East Europe and North America having the lowest and West Europe and Australasia the highest prevalence rates. Among post-menopausal women between 45 and 64 years, the prevalence of HRT use varied from 0 to 42%. In general, the use of HRT was high in Western and Northern Europe, North America and Australasia and low in Central, Eastern and Southern Europe and China. With the exception of Canada (45 years), the mean age at menopause differed only little (ranging from 48 to 50 years) between the populations.

The use of OC and HRT varies markedly between populations, in general following a regional pattern. Whereas, the prevalence rates are mostly similar within a country, there are remarkable differences even between neighbouring countries, reflecting nation-specific medical practice and public attitudes that are not necessarily based on scientific evidence.