There has been a remarkable global decline in the number of children women are having, say researchers.
Their report found fertility rate falls meant nearly half of countries were now facing a "baby bust" – meaning there are insufficient children to maintain their population size.
The researchers said the findings were a "huge surprise".
And there would be profound consequences for societies with "more grandparents than grandchildren".
How big has the fall been?
The study, published in the Lancet, followed trends in every country from 1950 to 2017.
In 1950, women were having an average of 4.7 children in their lifetime. The fertility rate all but halved to 2.4 children per woman by last year.
But that masks huge variation between nations.
The fertility rate in Niger, west Africa, is 7.1, but in the Mediterranean island of Cyprus women are having one child, on average.
In the UK, the rate is 1.7, similar to most Western European countries.
How high does the fertility rate have to be?
The total fertility rate is the average number of children a woman gives birth to in their lifetime (it's different to the birth rate which is the number of children born per thousand people each year).
Whenever a country's rate drops below approximately 2.1 then populations will eventually start to shrink (this "baby bust" figure is significantly higher in countries which have high rates of death in childhood).
At the start of the study, in 1950, there were zero nations in this position.
Prof Christopher Murray, the director of the Institute for Health Metrics and Evaluation at the University of Washington, told the BBC: "We've reached this watershed where half of countries have fertility rates below the replacement level, so if nothing happens the populations will decline in those countries.
"It's a remarkable transition.
"It's a surprise even to people like myself, the idea that it's half the countries in the world will be a huge surprise to people."
Which countries are affected?
More economically developed countries including most of Europe, the US, South Korea and Australia have lower fertility rates.
It does not mean the number of people living in these countries is falling, at least not yet as the size of a population is a mix of the fertility rate, death rate and migration.
It can also take a generation for changes in fertility rate to take hold.
But Prof Murray said: "We will soon be transitioning to a point where societies are grappling with a declining population."
Half the world's nations are still producing enough children to grow, but as more countries advance economically, more will have lower fertility rates.
'We'd rather give our daughter the best of everything'
Rachael Jacobs, 38, of Kent, had her first and only child seven years ago
I'd always focused on my career. When I was pregnant I was still focusing on my career.
I know now that we can survive on what we earn as a family and still go on holiday every year. If we had more than one child we couldn't go on holiday.
We'd rather give our daughter the best of everything than have multiple children that we can just about feed and clothe.
My partner and I are also thinking about the future. We want to be in a position where we can help her financially with university or housing. I don't want to ever have to say that she can't go to a party or have a new Christmas jumper.
Why is the fertility rate falling?
The fall in fertility rate is not down to sperm counts or any of the things that normally come to mind when thinking of fertility.
Instead it is being put down to three key factors:
- Fewer deaths in childhood meaning women have fewer babies
- Greater access to contraception
- More women in education and work
In many ways, falling fertility rates are a success story.
What will the impact be?
Without migration, countries will face ageing and shrinking populations.
Dr George Leeson, director of the Oxford Institute of Population Ageing, says that does not have to be a bad thing, as long as the whole of society adjusts to the massive demographic change.
He told the BBC: "Demography impacts on every single aspect of our lives, just look out of your window at the people on the streets, the houses, the traffic, the consumption, it is all driven by demography.
"Everything we plan for is not just driven by the numbers in the population, but also the age structure and that is changing, so fundamentally we haven't got our heads around it."
He thinks workplaces are going to have to change and even the idea of retiring at 68, the current maximum in the UK, will be unsustainable.
The report, part of the Global Burden of Diseases analysis, says affected countries will need to consider increasing immigration, which can create its own problems, or introducing policies to encourage women to have more children, which often fail.
Report author Prof Murray argues: "On current trends there will be very few children and lots of people over the age of 65 and that's very difficult to sustain global society.
"Think of all the profound social and economic consequences of a society structured like that with more grandparents than grandchildren.
"I think Japan is very aware of this, they're facing declining populations, but I don't think it's hit many countries in the West, because low fertility has been compensated with migration.
"At a global level there is no migration solution," Prof Murray says.
But while the change may challenge societies, it may also have environmental benefits given the impact of our species.
What about China?
China has seen huge population growth since 1950, going from around half a billion inhabitants to 1.4 billion.
But it too is facing the challenge of fertility rates, which stood at only 1.5 in 2017, and has recently moved away from its famous one child policy.
The reason developed countries need a fertility rate of 2.1 is because not all children survive to adulthood and babies are ever so slightly more likely to be male than female.
But in China, the report shows for every 100 girls born there were 117 boys which "imply very substantial sex-selective abortion and even the possibility of female infanticide".
That means even more children need to be born to have a stable population.
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NHS ‘should not prescribe acne drug’
The parents of young people who have killed themselves and patients unable to have sex are calling f..
The parents of young people who have killed themselves and patients unable to have sex are calling for the NHS to stop prescribing acne drug Roaccutane.
Ed Henthorn said it had caused him erectile dysfunction, psychosis and suicidal thoughts.
And one man who believes his son killed himself after taking the drug said the risks "are just too high".
Manufacturer Roche said "millions of patients worldwide have benefited from taking the drug".
The majority of those who take the drug have a positive experience.
"I used to think about girls… but my feelings, thoughts, just faded away," Ed Henthorn told the BBC's Victoria Derbyshire programme.
He was 19 when he took Roaccutane. He describes his acne as mild but bad enough to want to treat.
After three weeks he started to experience side-effects, including reduced energy and sex drive.
Then he experienced erectile dysfunction.
"That was why I decided to stop taking it," he said. (more…)
Spina bifida: Keyhole surgery repairs baby spine in womb
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In a UK first, doctors have used keyhole surgery to su..
In a UK first, doctors have used keyhole surgery to successfully repair the spine of a baby with spina bifida while it was still inside the womb.
Surgeons at King's College Hospital say the procedure is not a cure, but could be the difference between some children learning to walk or not.
Sherrie Sharp and her son Jaxson had the operation 27 weeks into the pregnancy.
Spina bifida was diagnosed after the routine 20-week pregnancy scans.
They showed Jaxson's spine and spinal cord were not forming correctly.
Gaps in the developing spine meant the cord was bulging out of his back and was left exposed to the amniotic fluid in the womb.
This damages the crucial nerves in the spinal cord and could lead to paralysis, a loss of sensation in the legs and problems controlling the bladder and bowels.
The longer the spinal cord is left exposed, the greater the damage.
Sherrie, 29, and from West Sussex, said the news was a shock, but an abortion was a "definite no". (more…)
Less chemotherapy better for older or frail patients with advanced stomach and oesophageal cancers
Less chemotherapy is as effective at controlling disease for elderly or frail patients with advanced..
Less chemotherapy is as effective at controlling disease for elderly or frail patients with advanced cancer of the stomach or oesophagus (food pipe), and leads to fewer side effects such as diarrhoea and lethargy. These are the results of a Cancer Research UK funded study, presented prior to the ASCO conference today (Wednesday).
“Increasingly were realising its not just age that affects how well someone can tolerate their treatment and we need to do more work to understand how other conditions or aspects of frailty might play a role.” – Dr Peter Hall, Cancer Research UK Edinburgh Centre[contfnewc]
Results from the GO2 trial could change the standard of care for patients who cant have full dose chemotherapy due to their age, frailty or medical fitness.
The study, which ran at hospitals all over the UK, coordinated from the University of Leeds, involved 514 people with stomach or oesophageal cancer. Their average age was 76 and the oldest was 96 years old. All were either frail, elderly or medically unfit, and for those reasons would be unlikely to tolerate full-strength treatment, which involves three chemotherapy drugs.
Patients went through a careful medical assessment, then went onto chemotherapy with just two drugs* and were allocated at random to receive them at either full-strength, medium-dose or low-dose. They were then carefully monitored to see how well the cancer was controlled, whether they had symptoms and side-effects, whether they felt their treatment was worthwhile, and what overall effect it had on their quality of life.
The researchers reported that the medium and lower doses of chemotherapy were as effective as the full-strength dose for controlling the cancer. But when the researchers looked at the overall effect of treatment, including quality of life, they reported that it was the lowest dose treatment that came out best.**
Around 15,800 people in the UK are diagnosed with stomach and oesophageal cancers every year***. Almost half (45%) of these people are 75 and over****. By 2035, this proportion is projected to rise to 55%*****, because of the UKs ageing population. This study, is one of few phase III trials in the country that seek to address how to best care for and treat this increasing population of elderly or frail cancer patients.
These findings also open up the possibility of more older and frail patients being able to take part in clinical trials.
Professor Charles Swanton, Cancer Research UKs chief clinician, said: “These valuable results reduce fears that giving a lower dose chemotherapy regimen is inferior and could make a huge difference for patients with stomach or oesophageal cancer who cant tolerate intensive courses of treatment.
“Older or frail patients are often not considered for new drug trials or standard of care therapy as theyre less able to tolerate combination chemotherapy. These trials are critical to provide much needed evidence on the effectiveness of new therapies and combination approaches, helping us develop new treatments for this growing group of patients.”
The researchers also assessed whether there were differences for the patients in the study who were under 75, or less frail, who might be expected to benefit from stronger treatment; but will be reporting that the lowest dose treatment gave the best results for them as well. (more…)
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