Page URL:

Mouse study may offer new clues to miscarriage risk

3 May 2011
Appeared in BioNews 605

A new study looking at the regulation of egg production in mice ovaries has identified a defect in 'quality control', which may help scientists understand why some women have a miscarriage during pregnancy.

Researchers at Washington State University in Pullman in the USA observed cell division, called meiosis, in immature eggs from mice. They found some eggs have an incorrect number of chromosomes and believe this phenomenon is also likely to be seen in humans.

Sperm or egg cells are formed through meiosis from a parent cell. During early meiosis, pairs of chromosomes align at the middle of the cell, called the meiotic spindle. The spindle assembly checkpoint (SAC) is a chemical signal that prevents cell division until all of the chromosomes are aligned.

The researchers found that in mice ovaries, the SAC trigger waits for a critical mass of chromosomes to be aligned rather than requiring that all the chromosomes align. This causes some eggs to have too many or too few chromosomes.

An abnormal number of chromosomes is a major risk factor for age-related miscarriages and birth defects, such as Down's syndrome. Dr Patricia Hunt, who led the study, said: 'We think that by the time a woman is in her 40s, about half the eggs she's ovulating are probably chromosomally abnormal. And for women in their 20s, it’s probably about ten percent. So it's a huge change'.

Dr Hunt believes the human body may allow defective eggs to divide because humans are evolutionarily programmed to prevent the loss of these precious cells. 'It is better to try and fail than to simply give up on an egg before it is even fertilised', she said.

Iha Nagaoka, co-author of the study, believes a screening method could be included in IVF treatment to check for abnormal eggs and help reduce the risk of miscarriage.

One in five pregnancies ends in miscarriage and the risk increases with mother's age.

Key factor to miscarriages confirmed
The Times of India |  3 May 2011
New clues to preventing miscarriage or pre-term births
New Scientist |  20 April 2011
Oocyte-Specific Differences in Cell-Cycle Control Create an Innate Susceptibility to Meiotic Errors
Current Biology |  26 April 2011
28 August 2012 - by John Brinsley 
Women who repeatedly reject pregnancies may be 'too good' at carrying, research indicates...
19 September 2011 - by Dr Lux Fatimathas 
International researchers have mapped over 55 million genetic variations in the mouse genome in the hopes of better understanding human disease. The genomes of 17 strains of mice were analysed and variations in their DNA, called SNPs, were catalogued...
18 April 2011 - by Mehmet Fidanboylu 
Researchers from Finland and the USA have identified a gene linked to an increased risk of premature birth. Previous research has looked at the mechanisms for synchronising fetal maturation and birth in animals...
7 March 2011 - by Dr Lucy Freem 
High levels of toxic polychlorinated biphenyls (PCBs), a man-made organic chemical associated with adverse health reactions in humans, in the blood may contribute to embryos failing to implant during IVF, say researchers....
6 September 2010 - by Chris Chatterton 
Researchers from Newcastle University have announced that they have a better understanding of 'why older women are more likely to produce abnormal eggs, increasing the risk of infertility...
to add a Comment.

By posting a comment you agree to abide by the BioNews terms and conditions

Syndicate this story - click here to enquire about using this story.