An Italian study of 2,822 post-menopausal women showed that the earliest age of menopause was found in women born in March and the latest among those born in October.

On average there was around 15 months' difference, with women born in October reaching menopause at over 50 years compared with under 49 years for women born in March.

The study, at four university hospitals, was carried out on 2,822 women who were at least a year past the menopause.

It found that the mean age of menopause was 49.42 – 49.04 for spring-born women and 49.97 for autumn-born women.

Angelo Cagnacci, at the University of Modena, said that they had controlled for factors likely to interfere significantly with the findings, such as age of menarche, weight, smoking etc., and independently of all these factors the age at menopause was conditioned by the season of birth.

He conceded that there were some limitations to the study, a possibility of recall bias, and it involved women referred to menopause centres rather than the general population. Also, the effect of seasons may differ in different geographic areas.

It was not known which seasonal environmental factors were capable of influencing timing of menopause via an action exerted before birth, or even before conception.

The study speculated that modifications of environmental temperature and sunlight may influence foetal growth and therefore future reproductive capabilities; seasonally linked diet modifications or exposure to infections were other possibilities.
Before conception, seasonal environmental factors influencing ooctye maturation may contribute to the development of defective embryos and weak adults.

" Our present data seem to indicate that women born in autumn develop better during their prenatal life and are born with a higher number of oocytes than women born in spring, " said Cagnacci. " An alternative explanation may be that early mortality is highest among children born in autumn, thus selecting the fittest for survival, although other studies do not support this hypothesis. "

According to researchers a prolonged reproductive period with a later menopause was an index of higher embryo quality and ultimately, their quality was passed on to their offspring.

Source: Human Reproduction, 2005


XagenaMedicine2005