Revealed: why risk of infertility and birth defects rises with age

Study pins blame on declining protein levels

Women who discover they cannot have children after trying to start a family too late have been given new hope by scientists in a major advance in understanding the causes of infertility.

Researchers at Newcastle University have uncovered the mechanism of "reproductive ageing" which causes female fertility to decline rapidly after the age of 35.

The discovery brings scientists a step closer to explaining why older mothers have less chance of conceiving and a greater risk of giving birth to an abnormal baby, and could point the way to a remedy. The research is published, with two other papers, in the journal Current Biology.

The trend of later motherhood is one of the most significant social developments of recent times, but it has brought heartache as an increasing number of women discover they have left it too late to have a baby.

Obstetricians have warned that the "bio-panic" women used to suffer on their 30th birthday has moved to their 40th, and have suggested that instead of searching for Mr Right they should perhaps settle for Mr Good Enough if they want a family.

Some experts have predicted that a fertility time bomb hangs over Britain over the coming decades as women delay childbearing. One in seven couples have problems conceiving, and this could rise to as many as one in three if present trends continue.

Births to women aged 35 and over have soared 56 per cent in the last decade and among women in their 40s by 90 per cent (to 2009). Down's syndrome pregnancies rose by more than 70 per cent in the 20 years to 2008, driven by the trend to later motherhood. Almost half of all births are to women of 35 and over today, but doctors say the "biologically optimal" time for childbearing is from 20 to 34.

The Newcastle study, led by Mary Herbert, reader in Reproductive Biology at the Institute of Ageing and Health, has shown that declining levels of proteins called cohesins, which act like a glue holding chromosomes together, are the key to reproductive ageing.

Loss of these proteins causes the chromosomes to split unevenly when eggs and sperm are being formed. To create eggs and sperm suitable for reproduction, the chromosomes must be halved equally. In eggs, the problem is compounded by the fact that the physical attachments holding the chromosomes together are established before birth and must be maintained by cohesins until the egg is created by cell division just before ovulation.

"Reproductive fitness in women declines dramatically from the mid-30s onwards. Our findings point to cohesin being a major culprit in this," Dr Herbert said.

She and her team compared egg creation in specially bred mice aged two and 14 months and found a "marked age effect".

"The aged mice we used are equivalent to a woman in her early 40s. Cohesin levels were very much reduced in eggs from older mice and the chromosomes underwent a messy division, resulting in the wrong number of chromosomes being retained in the egg."

She added: "We are at the stage of saying how the engine works and what is broken. The next stage is answering the question: can it be fixed? Could you add cohesin that would do the job [of holding the chromosomes together]? A lot of effort is going into answering that."

However, no solution to infertility was imminent. "The main message is for women not to delay childbirth. The best way for women to avoid the problem is to have their children earlier. If there are social reasons why they are delaying then we should look at these and make it easier for them."

Property
pets
Arts and Entertainment
tvGame of Thrones season 5 ep 4, review - WARNING: contains major spoiliers!
Arts and Entertainment
tvThe C-Word, TV review
Arts and Entertainment
The Ridiculous Six has been produced by Adam Sandler, who also stars in it
filmNew controversy after nine Native American actors walked off set
Life and Style
ebookNow available in paperback
ebooks
ebookPart of The Independent’s new eBook series The Great Composers
Sport
Danny Jones was in the Wales squad for the 2013 World Cup
rugby leagueKeighley Cougars half-back was taken off after just four minutes
Life and Style
The original ZX Spectrum was simple to plug into your TV and get playing on
techThirty years on, the ZX Spectrum is back, after a fashion
News
Tiger Woods and Lindsey Vonn are breaking up after nearly three years together
peopleFormer couple announce separation in posts on their websites
Sport
football
Life and Style
Google celebrates Bartolomeo Cristofori's 360th birthday
techGoogle Doodle to the rescue
Arts and Entertainment
Haunted looks: Matthew Macfadyen and Timothy Spall star in ‘The Enfield Haunting’
tvThe Enfield Haunting, TV review
News
news
News
The Mattehorn stands reflected in Leisee lake near Sunnegga station on June 30, 2013 near Zermatt, Switzerland
news
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?

ES Rentals

    Independent Dating
    and  

    By clicking 'Search' you
    are agreeing to our
    Terms of Use.

    iJobs Job Widget
    iJobs General

    Recruitment Genius: Senior Digital Marketing Consultant

    £28000 - £45000 per annum: Recruitment Genius: A Senior Digital Marketing Cons...

    Recruitment Genius: Assistant Stores Keeper

    £16640 - £18500 per annum: Recruitment Genius: An Assistant Stores Keeper is r...

    Recruitment Genius: Claims Administrator

    £16000 - £18500 per annum: Recruitment Genius: This is an excellent opportunit...

    Recruitment Genius: Software Developer - C# / ASP.NET / SQL

    £17000 - £30000 per annum: Recruitment Genius: Developer required to join a bu...

    Day In a Page

    Fishing for votes with Nigel Farage: The Ukip leader shows how he can work an audience as he casts his line to the disaffected of Grimsby

    Fishing is on Nigel Farage's mind

    Ukip leader casts a line to the disaffected
    Who is bombing whom in the Middle East? It's amazing they don't all hit each other

    Who is bombing whom in the Middle East?

    Robert Fisk untangles the countries and factions
    China's influence on fashion: At the top of the game both creatively and commercially

    China's influence on fashion

    At the top of the game both creatively and commercially
    Lord O’Donnell: Former cabinet secretary on the election and life away from the levers of power

    The man known as GOD has a reputation for getting the job done

    Lord O'Donnell's three principles of rule
    Rainbow shades: It's all bright on the night

    Rainbow shades

    It's all bright on the night
    'It was first time I had ever tasted chocolate. I kept a piece, and when Amsterdam was liberated, I gave it to the first Allied soldier I saw'

    Bread from heaven

    Dutch survivors thank RAF for World War II drop that saved millions
    Britain will be 'run for the wealthy and powerful' if Tories retain power - Labour

    How 'the Axe' helped Labour

    UK will be 'run for the wealthy and powerful' if Tories retain power
    Rare and exclusive video shows the horrific price paid by activists for challenging the rule of jihadist extremists in Syria

    The price to be paid for challenging the rule of extremists

    A revolution now 'consuming its own children'
    Welcome to the world of Megagames

    Welcome to the world of Megagames

    300 players take part in Watch the Skies! board game in London
    'Nymphomaniac' actress reveals what it was really like to star in one of the most explicit films ever

    Charlotte Gainsbourg on 'Nymphomaniac'

    Starring in one of the most explicit films ever
    Robert Fisk in Abu Dhabi: The Emirates' out-of-sight migrant workers helping to build the dream projects of its rulers

    Robert Fisk in Abu Dhabi

    The Emirates' out-of-sight migrant workers helping to build the dream projects of its rulers
    Vince Cable interview: Charging fees for employment tribunals was 'a very bad move'

    Vince Cable exclusive interview

    Charging fees for employment tribunals was 'a very bad move'
    Iwan Rheon interview: Game of Thrones star returns to his Welsh roots to record debut album

    Iwan Rheon is returning to his Welsh roots

    Rheon is best known for his role as the Bastard of Bolton. It's gruelling playing a sadistic torturer, he tells Craig McLean, but it hasn't stopped him recording an album of Welsh psychedelia
    Russell Brand's interview with Ed Miliband has got everyone talking about The Trews

    Everyone is talking about The Trews

    Russell Brand's 'true news' videos attract millions of viewers. But today's 'Milibrand' interview introduced his resolutely amateurish style to a whole new crowd
    Morne Hardenberg interview: Cameraman for BBC's upcoming show Shark on filming the ocean's most dangerous predator

    It's time for my close-up

    Meet the man who films great whites for a living