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."

News
peopleHowards' Way actress, and former mistress of Jeffrey Archer, was 60
Sport
Chelsea are interested in loaning out Romelu Lukaku to Everton again next season
sport
News
Robyn Lawley
people
Life and Style
Troy Baker and Ashley Johnson voice the show’s heroes
gamingOnce stilted and melodramatic, Hollywood is giving acting in video games a makeover
PROMOTED VIDEO
Life and Style
ebookA wonderful selection of salads, starters and mains featuring venison, grouse and other game
News
people
News
i100
Life and Style
Phones will be able to monitor your health, from blood pressure to heart rate, and even book a doctor’s appointment for you
techCould our smartphones soon be diagnosing diseases via Health Kit and Google Fit?
News
people
Extras
indybest
Sport
Usain Bolt confirms he will run in both the heats and the finals of the men's relay at the Commonwealth Games
commonwealth games
Life and Style
tech'World's first man-made leaves' could use photosynthesis to help astronauts breathe
Independent
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
santorini
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
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

    Senior Investment Accounting Change Manager

    £600 - £700 per day + competitive: Orgtel: Senior Investment Accounting Change...

    Microsoft Dynamics AX Functional Consultant

    £65000 - £75000 per annum + benefits: Progressive Recruitment: A rare opportun...

    Tax Solicitor

    £40000 - £70000 per annum + EXCELLENT: Austen Lloyd: Tax Solicitor An excel...

    Microsoft Dynamics AX Support Analyst

    £45000 - £50000 per annum + benefits: Progressive Recruitment: This is an exce...

    Day In a Page

    Save the tiger: The day America’s love of backyard tigers led to a horrific bloodbath

    The day America’s love of backyard tigers led to a horrific bloodbath

    With only six per cent of the US population of these amazing big cats held in zoos, the Zanesville incident in 2011 was inevitable
    Once stilted and melodramatic, Hollywood is giving acting in video games a makeover

    Acting in video games gets a makeover

    David Crookes meets two of the genre's most popular voices
    Could our smartphones soon be diagnosing diseases via Health Kit and Google Fit?

    Could smartphones soon be diagnosing diseases?

    Health Kit and Google Fit have been described as "the beginning of a health revolution"
    10 best over-ear headphones

    Aural pleasure: 10 best over-ear headphones

    Listen to your favourite tracks with this selection, offering everything from lambskin earmuffs to stainless steel
    Save the tiger: The animals bred for bones on China’s tiger farms

    The animals bred for bones on China’s tiger farms

    The big cats kept in captivity to perform for paying audiences and then, when dead, their bodies used to fortify wine
    A former custard factory, a Midlands bog and a Leeds cemetery all included in top 50 hidden spots in the UK

    A former custard factory, a Midlands bog and a Leeds cemetery

    Introducing the top 50 hidden spots in Britain
    Ebola epidemic: Plagued by fear

    Ebola epidemic: Plagued by fear

    How a disease that has claimed fewer than 2,000 victims in its history has earned a place in the darkest corner of the public's imagination
    Chris Pratt: From 'Parks and Recreation' to 'Guardians of the Galaxy'

    From 'Parks and Recreation' to 'Guardians of the Galaxy'

    He was homeless in Hawaii when he got his big break. Now the comic actor Chris Pratt is Hollywood's new favourite action star
    How live cinema screenings can boost arts audiences

    How live cinema screenings can boost arts audiences

    Broadcasting plays and exhibitions to cinemas is a sure-fire box office smash
    Shipping container hotels: Pop-up hotels filling a niche

    Pop-up hotels filling a niche

    Spending the night in a shipping container doesn't sound appealing, but these mobile crash pads are popping up at the summer's biggest events
    Native American headdresses are not fashion accessories

    Feather dust-up

    A Canadian festival has banned Native American headwear. Haven't we been here before?
    Boris Johnson's war on diesel

    Boris Johnson's war on diesel

    11m cars here run on diesel. It's seen as a greener alternative to unleaded petrol. So why is London's mayor on a crusade against the black pump?
    5 best waterproof cameras

    Splash and flash: 5 best waterproof cameras

    Don't let water stop you taking snaps with one of these machines that will take you from the sand to meters deep
    Louis van Gaal interview: Manchester United manager discusses tactics and rebuilding after the David Moyes era

    Louis van Gaal interview

    Manchester United manager discusses tactics and rebuilding after the David Moyes era
    Will Gore: The goodwill shown by fans towards Alastair Cook will evaporate rapidly if India win the series

    Will Gore: Outside Edge

    The goodwill shown by fans towards Alastair Cook will evaporate rapidly if India win the series