Younger eggs linked to increased lifespan?

New research from the University of Chicago in the US suggests that first-born children of young mothers have the best chance of living to 100; statistical results show this to be up to 1.7 times more likely than their siblings. Results were produced by studies from US Census, Social Security and other records, which aided in the reconstruction of family histories of just fewer than 200 centenarians born between the 1870's and 1890's.

The researchers showed that a strong predictor of longevity is having a young mother at the time of birth. These findings, presented at a meeting of the Gerontological Society of America in Dallas, show that children born before their mothers' 25th birthday were nearly twice as likely to live up to and beyond a century.

Dr Natalia Gavrilova, who co-led the research alongside husband Leonid Gavrilova, believes that this could be due to the better quality of eggs that are produced, and because it is less probable that the mother is likely to have acquired infections that might cause long-term damage to the health of the fetus. The team explains this by suggesting that in monthly menstrual cycles, women ovulate their best eggs first, and as they age, their supply of top-quality eggs diminishes and ovulation of lower-quality eggs commences.

Life expectancy for adults has risen sharply in the past 50 years. Average life expectancy in the 1950's for a man was 67 and women 73, this has continued to rise in 2005 to mid-70s for men and early 80s for women. Doctors have attributed this to better healthcare, nutrition and the fact that diseases like tubercolosis and polio have been almost wiped out.

Also reported last week was a study published in Nature suggesting how damaged eggs are weeded out. Scientists have identified 'p63', a protein that helps detect DNA damage in developing eggs. They believe it may play a key role in killing off defective eggs and ensuring only the healthy ones may be fertilised.

The Harvard Medical School research was undertaken on developing mouse eggs where meiotic cell division was studied (which results in a mature egg containing just one set of chromosomes). The research involved exposing egg cells to radiation to cause damage to the DNA. Lead researcher Dr Frank McKeon said: 'p63... is the critical factor for monitoring the level of DNA damage in oocytes...' The researchers say that this work sheds light on the process by which the ovary can quality-control the eggs it contains, to make sure that damaged ones are not ovulated.

Dr Allan Pacey, senior lecturer at the University of Sheffield and secretary of the British Fertility Society says, 'This work might one day allow us to understand why some women have fertility problems because of the poor quality of the eggs they ovulate'.