"The Exact Mechanism Remains a Mystery"
--Vital Signs --
From The Pussy Cat
Patterns: Predicting Menopause by Month
By NICHOLAS BAKALAR
Published: May 17, 2005 NYTimes
The age at which a woman will reach menopause can be predicted by the month in which she was born, Italian researchers report.
The researchers examined the health records of more than 2,800 women for whom they could precisely date the age when menopause began. After adjusting for other factors, the study found that women born in March reached menopause at the youngest age, and for each birth month between March and October, the age of menopause increased.
On average, women born in October reached menopause at the oldest age, 15 months later than those born in the spring. The study was published in the May issue of the journal Human Reproduction.
A woman's fertility is limited by the number of eggs that are formed before birth and by how quickly the eggs degenerate as she ages. These physiological mechanisms can presumably be influenced by environment during gestation.
Dr. Angelo Cagnacci, associate professor at the University of Modena and the lead author on the study, said that while shortages or abundance of food available to mothers at different times of year probably were not a factor in industrialized countries, the changing seasons might bring diet modifications "that may favor a better or worse fetal development."
Dr. Cagnacci speculated that infections that had a seasonal pattern might also affect the fetus and that temperature might play a role by altering placental blood flow at critical periods of development. But the exact mechanisms remain a mystery.