The age-old birth debate
With reports that Carla Bruni is pregnant at 43, Lisa Salmon hears the arguments for and against late motherhood.
Growing evidence that France's First Lady, Carla Bruni, is pregnant makes her the latest in a long list of older celebrity mums.
Former supermodel Bruni, 43, joins famous faces including Madonna, who had her last child at the age of 41; Cherie Blair, who had son Leo at 45; and Jo Brand, who gave birth to daughters at the age of 43 and 45.
Putting off pregnancy seems to be a growing trend - births to women in their forties have soared by 90pc and by 56pc among over-35s in the last decade.
But having children later in life doesn't come without its dangers, for both mother and baby alike, which can include high blood pressure and birth defects.
Bruni and her husband, President Nicolas Sarkozy, have remained tight-lipped about the pregnancy so far (it's only been confirmed by relatives), so it's not known whether she conceived the old-fashioned way, or had fertility treatment.
But if it is a natural conception, medical evidence suggests Bruni is lucky, as fertility drops dramatically after the age of 35, and by 40 women are half as fertile as they were at 35, according to the Human Fertilisation and Embryology Authority.
Author Claudia Spahr is one of the growing number of women who have defied the odds - she had her first baby at the age of 40, and is now six months pregnant with her second child, which is due just before she turns 43.
Spahr has just written the book Right Time Baby, a guide to later motherhood in which she controversially insists there is "no clear data proving that it's harder to get pregnant when you're older, even though most doctors will relay it as fact".
Consultant obstetrician Dr Virginia Beckett is one such doctor, and she says the evidence for fertility declining with age is "indisputable".
But Spahr counters: "Women haven't been actively trying to get pregnant in their forties before - it's quite a new phenomenon, and no proper studies have been done. It's a very individual thing."
She did a small survey for the book of 60 mothers aged between 35 and 50, asking them how quickly they got pregnant.
The results showed that 65pc got pregnant faster than three months, and it took just 15pc longer than eight months to conceive.
"That just goes to show that it can be easy," she asserts.
However Beckett, who's based at Bradford Royal Infirmary, says that while some older women may get pregnant quickly, fertility certainly does dramatically decline with age for most women.
"In populations it drops, in individuals it's much more difficult to predict," she explains.
Beckett runs an IVF unit, and illustrates the drop in fertility with the fact that the chances of a woman in her twenties conceiving through IVF are 40pc per cycle, but a woman in her forties has just a 10pc chance, dropping to about 3pc by the age of 43.
She says tests can assess a woman's fertility, but warns: "My clinics are full of people who thought that they had time, and they didn't.
"For some people that's because they didn't meet the right person. But if people are in the right relationship and they're ready, I would suggest they get pregnant sooner rather than later."
Ideally, this would be before the age of 35, she says.
This is because as well as it being more difficult for older women to conceive, later pregnancy also brings increased risk of complications.
These include high blood pressure, gestational diabetes, premature labour and bleeding disorders such as placental abruption (when the placenta detaches from the uterus).
However, Spahr says her survey showed complications among older mothers were at a similar rate to younger mums.
But Beckett points out that when a woman gets to her forties, "things are starting to wear out".
This includes the pancreas, which means there's an increased risk of diabetes in pregnancy, and blood vessels, which increase the risk of blood pressure problems and blood clots.
As well as potential maternal complications, pregnancy later in life brings an increased risk of foetal abnormalities, particularly chromosomal problems like Down's Syndrome.
While around one in a thousand babies born to mothers under 30 have Down's, the figure rises to one in 400 by the age of 35, and one in 105 by the age of 40.
Down's Syndrome pregnancies rose by more than 70pc in the 20 years to 2008, seemingly driven by the trend to later motherhood.
But Spahr insists there's plenty that prospective older mothers can do to improve the quality of their eggs, and thus reduce the risk of chromosomal abnormalities, or miscarriage, which is also a much higher risk for older mothers.
She suggests a fruit and veg juice detox a few months before trying to conceive, to cleanse the body of accumulated toxins.
When not fasting, she recommends organic foods, including plenty of fruit and vegetables eaten raw when possible, and lots of water, plus foods containing essential fatty acids, omega-rich oils, and antioxidants.
In addition, she says it's important to exercise, and cut back on processed foods and caffeine.
And both women and men who want to conceive should greatly reduce their alcohol intake, and quit smoking.
She says: "There's good medical evidence showing that good nutrition and a healthy lifestyle has a big effect on the quality of your eggs."
Conversely, Beckett says there's no evidence to show that improving diet and lifestyle makes a huge difference to the quality of a woman's eggs, although smoking does irreversibly affect ovarian ageing.
A good diet can help reduce problems like spina bifida, if folic acid supplements are taken.
But she stresses: "A good diet and exercise help you be healthy in pregnancy, but the reason the vast majority of abnormalities and miscarriages happen in older mothers is because of a chromosomal problem.
"That's a very grass roots problem that's not going to be altered by things like diet.
"It can make a difference, but it's not going to make a massive difference."
Spahr warns older women who do have healthy pregnancies not to get too anxious because they're classed as high-risk, suggesting that such anxiety is felt by medical staff too, and is one of the reasons why older women have more Caesarean births.
"Don't panic - that sends all the wrong messages to your body," she says.
"Instead of listening to all the warnings about the limitations we face, we should start exploring all the possibilities we actually do have.
"If you believe you're healthy and you back it up by looking after yourself, you stand a very good chance of having a healthy baby."
But Beckett warns: "I see many women in their late thirties who aren't having problems conceiving, but are having problems delivering babies because they miscarry early, possibly because of foetal chromosomal disorders. It's a big issue."
If a later pregnancy is a woman's only option, then planning is important, she says. This includes looking at improving diet and exercise, and thinking carefully about screening tests such as amniocentesis or Chorionic villus sampling (CVS), which can detect foetal chromosomal abnormalities but have a small miscarriage risk.
She adds: "There's no getting away from the fact that pregnancy in your forties is riskier and you'll need more support."