Nine Swedish women have received womb transplants from living relatives in a pioneering trial.
Dr. Mats Brannstrom, of the University of Gothenberg, who has been leading the experimental fertility project, hopes the technique could help other women who want to become pregnant.
This includes women either born without a womb or who have womb problems that stop them conceiving.
Dr. Mats Brannstrom’s team recruited 10 women to their trial. One could not proceed with the trial for medical reasons, but nine went on to have a womb transplant.
These women were born without a uterus or had it removed because of cervical cancer.
Most are in their 30s and are part of the first major experiment to test whether it is possible to transplant wombs into women so they can give birth to their own children.
Nine Swedish women have received womb transplants from living relatives in a pioneering trial
There have been two previous attempts to transplant a womb – in Turkey and Saudi Arabia – but both failed to produce babies.
“This is a new kind of surgery,” Dr. Mats Brannstrom told Associated Press in an interview from Gothenburg.
“We have no textbook to look at.”
Dr. Mats Brannstrom and colleagues will run the first workshop on how to perform womb transplants and they plan to publish a scientific report on their efforts soon.
The transplant operations did not connect the women’s uteruses to their fallopian tubes, so they are unable to become pregnant naturally. But all who received a womb have their own ovaries and can produce eggs to be used for IVF treatment.
An often-cited statistic says that one out of three women over the age of 35 will not have conceived after a year of trying.
Jean Twenge, a psychologist at San Diego State University in the US, was 34, recently remarried, and looking to start a family, when she heard it from her doctor.
“That was very frightening to me, as it is too many women who are in their 30s,” she says.
Confronted with those odds, Jean Twenge wanted to find out where the statistic had come from. And she discovered something quite amazing.
“The data on which that statistic is based is from 1700s France. They put together all these church birth records and then came up with these statistics about how likely it was [someone would] get pregnant after certain ages.”
These are women who had no access to modern healthcare, nutrition or even electricity. Why would any researcher think they can tell us something useful about modern-day fertility?
Well, actually, they do have one big advantage. They weren’t using effective methods of birth control.
“I can empathize slightly with the researchers in this area,” says Jean Twenge, who traced the source of the data as she researched her book, An Impatient Woman’s Guide to Getting Pregnant. “It is difficult to draw conclusions about age and fertility from modern populations where birth control is widely used.”
However, there are some studies which have looked at modern couples, and these do paint a rather different picture.
The most widely cited is a paper by David Dunson published in 2004, which found that 82% of women aged between 35 and 39 fell pregnant within a year. That’s significantly better than the two-thirds chance drawn from the 300-year-old birth records.
David James of the UK’s National Institute for Health and Care Excellence (NICE) fertility guideline development group says: “It was a single study undertaken relatively recently of about 780 women, in seven different European centres. The important point about that was that these were women who were trying to conceive.”
An often-cited statistic says that one out of three women over the age of 35 will not have conceived after a year of trying
The main problem with the historic data, in David James’s view, is that the women may not have been trying to conceive.
Indeed, they may have been actively trying to avoid becoming pregnant. They may not even have had intercourse.
“There’s no doubt that intercourse becomes less frequent the older the couple are,” David James says. And in the 1700s, people aged more quickly than today.
Another finding of David Dunson study was that, while fertility declines with age, it does not appear to do so as quickly as we have been led to believe.
Among women aged 27-34, the study showed that 86% will have conceived within a year of trying. So the 82% figure for women aged 35 to 39 is only a little lower.
After that, the picture is a little less clear.
“It would appear from the limited and poor quality data that we have that that rate falls significantly [at 40]. But as we know from some notable celebrity cases, it is not impossible to get pregnant in the early or indeed late 40s,” says David James.
And, he adds, there is evidence that female fertility is improving.
The latest update of the NICE guideline on fertility recognizes that “the chances of women naturally conceiving at the age of 40 are much higher now than they were when the original guideline was written [in 2004],” David James says.
What about the risk of chromosomal abnormalities, such as Down’s syndrome? It’s possible that this has been overstated too, in David James’s view.
The chance of any chromosomal abnormality at the age of 20 is one in 500, he says.
That increases to one in 400 at the age of 30, and one in 60-70 at age 40.
“Turning that on its head, it does mean that 59 out of 60 women aged 40 will have no chromosomal problems in their baby at all.”
So while it’s harder for older women to get pregnant, and the chance of a chromosomally abnormal child increases, these problems do not increase as sharply as we fear – except perhaps for those trying IVF or artificial insemination.
“Those statistics are more discouraging for older women,” explains Jean Twenge.
“The difference in success rates in IVF between your early 30s and your late 30s is a lot bigger than the difference in success in natural conception.”
Similarly with artificial insemination – the data shows that the success rates just are not as high as natural conception rates and can differ by as much as 20 percentage points.
But many fertility problems that women over 30 experience have nothing to do with age. Had they tried to conceive in their 20s, they would have also faced difficulties.
“I think that doctors who give blanket advice to populations… are making all sorts of presumptions,” says leading fertility expert Prof. Lord Winston.
“We eventually find out that so much of this advice is spurious and unnecessary and often wrong.”
So is there any “blanket” fertility advice he can give?
“The fact of the matter is, the best way to have a baby is either in bed or by the fireside on the hearth rug.”
However, a UK expert said that was the “wrong way round” and men chose younger women because older women were less fertile.
Researchers have long been puzzled as to why it appears that human are the only species where females cannot reproduce throughout their lives.
Previous theories had proposed a “grandmother effect”. This suggests that women lose their fertility at an age where they might not live to see a child grow, and instead are available to care for younger women’s children.
The menopause was therefore seen as the block to older women from continuing to reproduce.
But this latest theory suggests things work the other way around, and that it is the lack of reproduction that has given rise to menopause.
Evolutionary geneticists from McMaster University say men’s tendency to choose younger mates meant fertility became pointless for older women
Using computer modelling, the team from McMaster’s concluded “preferential mating” was the evolutionary answer – men of all ages choosing younger women as partners.
That meant there was “no purpose” in older women continuing to be fertile.
Prof. Rama Singh, an evolutionary geneticist who led the study, said men choosing younger mates were “stacking the odds” against continued fertility.
He said: “There is evidence in human history; there was always a preference for younger women.”
Prof. Rama Singh stressed they were looking at human development many thousands of years ago – rather than current social patterns,
He said this extended longevity – plus later childbirth – could potentially alter the timing of the menopause, over a significant period of time.
“The social system is changing. There are women who are starting families later, because of education or a career.”
Prof. Rama Singh suggested this trend would mean those women would have a later menopause, and those genes would be passed on to their daughters “with the possibility of menopausal age being delayed”.
However, Dr. Maxwell Burton-Chellew, an evolutionary biologist in the department of zoology at the University of Oxford, challenged the theory.
“The authors argue that the menopause exists in humans because males have a strong preference for younger females.
“However, this is probably the wrong way round – the human male preference for younger females is likely to be because older females are less fertile.
“I think it makes more sense to see the human male preference for younger females largely as an evolved response to the menopause, and to assume that ancestral males would have been wise to mate with any females that could produce offspring.”
Dr. Maxwell Burton-Chellew added: “Evolutionarily-speaking, older females faced an interesting ‘choice’: have a child that may not reach adulthood before your own death, or stop reproducing and instead focus on helping your younger relatives reproduce.”
A team of doctors claim that “super-fertility” may explain why some women have multiple miscarriages.
They say the wombs of some women are too good at letting embryos implant, even those of poor quality which should be rejected.
The UK-Dutch study published in the journal PLoS ONE said the resulting pregnancies would then fail.
One expert welcomed the findings and hoped a test could be developed for identifying the condition in women.
A team of doctors claim that "super-fertility" may explain why some women have multiple miscarriages
Recurrent miscarriages – losing three or more pregnancies in a row – affect one in 100 women in the UK.
Doctors at Princess Anne Hospital in Southampton and the University Medical Center Utrecht, took samples from the wombs of six women who had normal fertility and six who had had recurrent miscarriages.
High or low-quality embryos were placed in a channel created between two strips of the womb cells.
Cells from women with normal fertility started to grow and reach out towards the high-quality embryos. Poor-quality embryos were ignored.
However, the cells of women who had recurrent miscarriages started to grow towards both kinds of embryo.
Prof. Nick Macklon, a consultant at the Princess Anne Hospital, said: “Many affected women feel guilty that they are simply rejecting their pregnancy.
“But we have discovered it may not be because they cannot carry, [but] it is because they may simply be super-fertile, as they allow embryos which would normally not survive to implant.”
He added: “When poorer embryos are allowed to implant, they may last long enough in cases of recurrent miscarriage to give a positive pregnancy test.”
This theory still needs further testing and will not explain all miscarriages.