Male fertility doesn’t last forever.
While it’s well known that women start to experience a decline in fertility in their thirties, scientists have found new evidence suggesting men also have a ‘biological clock‘ that limits their ability to reproduce as they get older.
A new study shows that in vitro fertilisation (IVF) delivery rates are affected by the age of the male partner, with successful IVF procedures becoming less likely as would-be fathers get older.
Dodge’s team analysed 15 years’ worth of IVF treatments conducted in Boston between 2000 and 2014, encompassing some 19,000 IVF cycles performed for almost 8,000 couples.
What they found is that as the males in the couples got older, the chances of live birth were reduced – but the effect was only apparent in couples where the woman wasn’t older than 40.
From the data set, the researchers divided the IVF participants (both male and female) into four age bands: under 30, 30–35 years old, 35–40, and 40–42.
The cumulative live birth rate – measured from up to six cycles of IVF treatment – was lowest in couples where the female partner was aged 40–42, which wasn’t a surprise, given what we know about decreasing female fertility as women age.
In this band, where females were aged 40–42, the age of the male partner had no impact on birth rate, but in the younger female bands, cumulative live birth rates were found to decline as male partners grew older.
“However, women aged 35–40 did significantly benefit from having a male partner who is under age 30, in that they see a nearly 30 percent relative improvement in cumulative incidence of live birth when compared to women whose partner is 30–35 – from 54 percent to 70 percent.”
And just as birth outcomes were more successful when older females paired with younger males, they stood a greater chances of failure when younger females attempted IVF with older males.
In the study, couples where the female partner was under 30 and the male was aged 40–42 had a cumulative birth rate of 46 percent, but if the male partner’s age was 30–35, this improved significantly to 73 percent.
“Where we see significant decreases in the cumulative incidence of live birth is among women with male partners in the older age bands,” says Dodge.
“For women age 30–35, having a partner who is older than they are is associated with approximately 11 percent relative decreases in cumulative incidence of live birth – from 70 percent to 64 percent – when compared to having a male partner within their same age band.”
As for why older males enjoy less success with IVF, the researchers aren’t entirely sure and intend to pursue the question further, but suggest it could be related to damaged sperm that affect fertility prospects as men get older.
While the effects reported here are significant, it’s worth pointing out that the study – which is being presented this week at the annual meeting of the European Society of Reproduction and Embryology in Switzerland – hasn’t yet been peer-reviewed by other scientists, so we should bear that in mind when considering the findings.
But in the meantime, researchers say these preliminary results could help would-be parents to consider the broader range of factors that may affect their family prospects – and which aren’t simply limited to how old the female partner is.
“The value of this is not only in counselling couples,” obstetrician Nick Macklon from the University of Southampton in the UK, who was not involved in the study, told Ian Sample at The Guardian.
“It may help women to encourage their male partners to get a move on. We know from a number of studies that one of the reasons why women are having babies later is because men are sometimes slow to support the idea. This reminds us that it takes two to tango and it’s not just down to the age of the woman.”
Babies born to older mothers are more likely to be healthy if they have been conceived through IVF rather than naturally, a major new study has found.
A survey of more than 300,000 live births revealed that women aged 40 or over were more than twice as likely to have a child with birth defects than those of the same age who had undergone a widely used method of assisted reproduction.
Scientists behind the study say the “remarkable” findings may be explained by a hormonal stimulation provided by IVF that helps reverse the decline in ovulation control experienced as women get older.
The team from the University of Adelaide collated data from every live birth in South Australia between 1986 and 2002, which revealed that the overall proportion of birth defects among naturally conceived babies across all age groups was 5.7 per cent, compared to 9.9 per cent for traditional IVF births.
For babies conceived using Intracytoplasmic sperm injection (ICSI), a variety of IVF used in about 70 per cent of cases worldwide, just under 10 per cent had birth defects.
For women aged 40 or over, however, the relative likelihood of having a healthy baby reversed, with an 8.2 per cent chance of birth defects for those conceived naturally against just a 3.6 per cent chance for those conceived using ICSI.
Professor Michael Davies, who led the research, said: “There is something quite remarkable occurring with women over the age of 40 who use assisted reproduction.
“There is some aspect of IVF treatment in particular that could be helping older women to redress the maternal age issues we see among natural conception, where we observe a transition at around the age of 35 towards a steadily increasing risk of birth defects.
“We don’t know what that is quite yet – it could be an aspect of hormonal stimulation that helps reverse the age-related decline in control of ovulation.”
The study also revealed that the age at which women who are treated with both IVF and ICSI combined are most at risk of giving birth to an unhealthy child is 29, with a 9.4 per cent chance.
Professor Davies said his findings could have significant implications for infertility treatment if researchers can understand why older women do better on assisted reproduction.
However, Yacoub Khalaf, a consultant gynaecologist at Guys and St Thomas’s hospitals in London, pointed out that, despite the size of the overall study, the number of births in the over 40 group were “relatively small”, and said Professor Davies’ inferences could be the result of a statistical anomaly.
Success rates in IVF cycles using frozen and thawed embryos are now equal to those using fresh embryos, a new report on reproductive technology (ART) treatments in Australia and New Zealand has found.
In the five years leading up to 2013, the birth rate for frozen embryo transfers grew by a quarter to 23 percent, whereas the rate of fresh embryo IVF cycles that led to a baby remained steady, also at 23 percent. Effectively, both methods now offer equal chances of a successful birth for parents looking into IVF.
In addition to success rates for frozen embryos rising, Australian and New Zealand parents are also turning to the technique in greater numbers, with IVF treatments using frozen embryos increasing from 39 percent of IVF cycles in 2009 to 45 percent in 2013.
The figures are contained in the Assisted Reproductive Technology in Australia and New Zealand 2013 report, authored by researchers at the University of New South Wales (UNSW) in Australia.
“Rapid freezing techniques, known as vitrification, and optimisation of the timing of embryo transfer have made a real difference to the success of frozen embryo birth rates,” said Michael Chapman, a professor of obstetrics and gynaecology at UNSW and vice-president of the Fertility Society of Australia (FSA), in a press release.
“Other techniques, such as culturing embryos for five to six days to a blastocyst, before transfer to a woman, and the use of pre-implantation genetic screening have also increased over the last five years of reporting,” said Chapman.
Another significant trend observed in the figures is a marked reduction in multiple births in IVF treatments, which have decreased by a third in the past five years to 5.6 percent in 2013.
Multiple births result in the delivery of twins, triplets, or higher-order multiples. As women age, they are more likely to experience multiple births, as their bodies may release more than one egg in order to fall pregnant – and the likelihood of multiple births is also significantly increased by the use of IVF and fertility treatments. However, delivering multiple babies can be dangerous to both a mother and her infants.
“Multiple births are by far the greatest health risk to mothers and babies from IVF, and multiple embryo transfer clearly increases this risk,” said Chapman. “This is one of the lowest rates of multiple deliveries from IVF treatment in the world.”
By comparison, the multiple birth rate is 16 percent in the UK and 26 percent in the US.
According to Chapman, the new figures suggest that Australia and New Zealand are the safest regions in the world for women to undergo IVF treatments. “Australia and New Zealand have the lowest IVF multiple birth rates of any region in the world,“ he said, ”and yet also maintain consistently high success rates.”