London, Sep 5 (IANS): Scientists have discovered why women are more likely to suffer from miscarriages and infertility problems if they try to have babies later in life.

Their study also sheds light on why children born to women in their late 30s and early 40s are at greater risk of Down's Syndrome and other genetic conditions, reports dailymail.co.uk.

The team of British researchers found that as a woman gets older, levels of a crucial protein that helps eggs prepare for the moment of fertilisation decline sharply. The drop increases the risk that an egg will end up with wrong number of chromosomes and be faulty.

The finding raises the prospect of new drugs to help keep eggs healthy as women get older.

Girls are born with a set of immature egg cells that will last for their entire reproductive life.

Each immature egg contains two sets of 23 chromosomes - the chains of DNA that contain instructions on how to build and maintain a human being.

Before the eggs can be fertilised, they must complete a complex process of 'ripening' called meiosis in which half of these chromosomes are ejected.

The resulting egg cell contains only 23 strands of DNA - the genes passed down from a mother to her child.

The most important stage of meiosis happens just before ovulation when a large amount of DNA is ejected from the egg. If it goes wrong, an egg can be left with the wrong number of chromosomes, the experts said.