A study of nearly 3,000 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.
Writing in Europe's leading reproductive medicine journal Human Reproduction, lead author Dr Angelo Cagnacci said that the findings reinforced the concept that prenatal environmental factors affected a baby's adult life.
"Mothers should be aware of this, considering that during pregnancy they are going to influence, not only the health of the newborn, but also the health and reproductive life of their child during adulthood," he said.
The study, at four university hospitals (Bologna, Ferrara, Modena and Parma), 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.
Dr Cagnacci, associate professor of Obstetrics and Gynaecology 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.
"Nevertheless, the data seem to suggest notable effects of the month/season of birth on the length of a woman's fertile life, further supporting a ro