Chromosome key to later fertility

Science | Health - Cath Harris | 19 Nov 10. New research at Oxford University has shed light on how mammalian egg cells divide. The findings may lead to improvements in women's chances of giving birth to healthy babies as they get older. After the age of 33, the likelihood of a woman producing healthy eggs and embryos declines dramatically but little is known of the reasons why. In younger women, the pairing off, or segregation, of chromosomes in precursor cells usually produces eggs with a complete set of chromosomes. Fertilisation of these eggs would tend to produce viable embryos. But, as women age, chromosome segregation becomes faulty and eggs can be produced with the wrong number of chromosomes.