abdulhakeem
17-06-04, 01:50 PM
14:17 17 June 04
Shaoni Bhattacharya
NewScientist.com news service
Scientists may soon be able to calculate how long a woman has left before menopause, suggests a new study.
UK researchers have shown a strong link between the size of a woman's ovaries and the number of eggs she has left.
Hamish Wallace and Thomas Kelsey used this link to create a model that should be able to predict a woman's "reproductive age" to within one or two years using her chronological age and a measure of the size of her ovaries. Ovarian volume can be measured with a simple ultrasound technique that doctors already use to examine the organs.
"In essence, it means we now have the potential to be able to tell a woman how fast her biological clock is ticking and how much time she has before it will run down," says Wallace, at the Royal Hospital for Sick Children in Edinburgh, UK, and a lecturer at Edinburgh University.
"The accurate assessment of ovarian reserve will revolutionise the management of women requesting assisted conception, those who have had treatment for childhood cancer and those who are considering delaying a family for personal or professional reasons," suggest the pair.
Rapid fall-off
The conventional view is that women are born with a fixed number of eggs in their ovaries. Studies show that the number of eggs peaks when a female fetus is just five months old. After this, the number of eggs declines as they age and die by a process known as atresia.
When the number of eggs left reaches about 25,000 ? corresponding on average to the age of 37 ? there is a more rapid fall-off in their numbers. This key point usually precedes menopause by about 12 to 14 years. There are only about 1000 eggs left by the time a woman reaches menopause.
The average age of menopause is about 50 to 51, with 95 per cent of women reaching menopause between the ages of 42 and 58, says Kelsey, a mathematician at the University of St Andrews. But some women can experience menopause before this.
Reproductive age
Wallace and Kelsey used published data showed that the larger the ovary, the more eggs a woman has. The pair assume that the large difference in the ages at which women undergo the menopause results from the difference in how the number of eggs they had at birth.
They then modelled data from additional studies to produce a prediction chart. "We were trying to make the distinction between your chronological age and your reproductive age," Kelsey told New Scientist. "A 40-year-old woman could be anything between 32 and 48 ."
The size of a woman's ovaries can be measured by a commonly used technique called transvaginal ultrasound. "The big thing about this technique is that it is non-destructive and cheap and widely available," Kelsey points out. "It's practical."
Kelsey says they are "optimistic" about developing the model as a prediction tool, but notes that more tests are needed to validate the accuracy of the method.
[I]Journal reference: Human Reproduction (vol 19, p 1613)
http://www.newscientist.com/news/news.jsp?id=ns99996029
Shaoni Bhattacharya
NewScientist.com news service
Scientists may soon be able to calculate how long a woman has left before menopause, suggests a new study.
UK researchers have shown a strong link between the size of a woman's ovaries and the number of eggs she has left.
Hamish Wallace and Thomas Kelsey used this link to create a model that should be able to predict a woman's "reproductive age" to within one or two years using her chronological age and a measure of the size of her ovaries. Ovarian volume can be measured with a simple ultrasound technique that doctors already use to examine the organs.
"In essence, it means we now have the potential to be able to tell a woman how fast her biological clock is ticking and how much time she has before it will run down," says Wallace, at the Royal Hospital for Sick Children in Edinburgh, UK, and a lecturer at Edinburgh University.
"The accurate assessment of ovarian reserve will revolutionise the management of women requesting assisted conception, those who have had treatment for childhood cancer and those who are considering delaying a family for personal or professional reasons," suggest the pair.
Rapid fall-off
The conventional view is that women are born with a fixed number of eggs in their ovaries. Studies show that the number of eggs peaks when a female fetus is just five months old. After this, the number of eggs declines as they age and die by a process known as atresia.
When the number of eggs left reaches about 25,000 ? corresponding on average to the age of 37 ? there is a more rapid fall-off in their numbers. This key point usually precedes menopause by about 12 to 14 years. There are only about 1000 eggs left by the time a woman reaches menopause.
The average age of menopause is about 50 to 51, with 95 per cent of women reaching menopause between the ages of 42 and 58, says Kelsey, a mathematician at the University of St Andrews. But some women can experience menopause before this.
Reproductive age
Wallace and Kelsey used published data showed that the larger the ovary, the more eggs a woman has. The pair assume that the large difference in the ages at which women undergo the menopause results from the difference in how the number of eggs they had at birth.
They then modelled data from additional studies to produce a prediction chart. "We were trying to make the distinction between your chronological age and your reproductive age," Kelsey told New Scientist. "A 40-year-old woman could be anything between 32 and 48 ."
The size of a woman's ovaries can be measured by a commonly used technique called transvaginal ultrasound. "The big thing about this technique is that it is non-destructive and cheap and widely available," Kelsey points out. "It's practical."
Kelsey says they are "optimistic" about developing the model as a prediction tool, but notes that more tests are needed to validate the accuracy of the method.
[I]Journal reference: Human Reproduction (vol 19, p 1613)
http://www.newscientist.com/news/news.jsp?id=ns99996029