Men have biological clocks too, it turns out. But because we live in a society obsessed with male virility, it is a taboo topic.
These are the findings of a six-year research project by Cambridge University sociologist, Liberty Walther Barnes.
She spent more than 100 hours shadowing specialists in infertility and interviewing 24 couples having difficulties conceiving. She concluded that fertility treatments tended to be directed at women, while men tended to be in denial about their possible role in it.
Despite all the men she interviewed presenting with low or zero sperm counts, more than half of them did not consider themselves infertile.
Bolstering the idea that increasing infertility is a female issue is that, in the US at least, there is only about one male specialist for every five reproductive endocrinologists.
"Ultimately, it's the woman who has to get pregnant and carry the baby, so reproductive medicine has historically focused primarily on women's bodies," Barnes said in an interview with The Atlantic.
This wasn't to blame men, she said, but to highlight a socially entrenched stance that needed to change.
"If we look at the history of reproductive biomedicine and representations of infertility in the media, popular culture and public discourse, it's as if male infertility doesn't exist in our social world," she said.
"The 'invisibility of male infertility' phenomenon was reflected in the attitudes, lives and identities of the men I was interviewing.
"Male infertility is presumed to be terribly emasculating for men, and it is socially taboo to discuss it.
"Doctors strive to protect their patients' masculinity by using soft language. Wives tread gently regarding their husband's fertility issues. And something about the availability of infertility treatments reassures men that a problem that can be fixed isn't a problem."
Interestingly, while men were often not even offered treatment or considered in the process, when they were they were willing participants.
"When couples were given the choice to pursue a female-focused treatment, like IVF, or a male-focused treatment, like surgery, they unanimously chose the male treatment first," Barnes said in the full interview.
"There was a strong sense among women and men that male-focused treatments were a more 'natural' solution to achieving pregnancy and that physical participation in treatments was a manly way for men to protect their wives."
In exploring these issues in her coming book Conceiving Masculinity: Male Infertility, Medicine, and Identity, Barnes argues that two big gender myths must be reassessed: that women will do anything to become pregnant and that men will do anything to avoid fertility treatment.
In Australia, more than a third of men aged over 40 report having one or more reproductive health problems.
About one in 20 men in Australia are infertile, and about one in 200 suffer from low testosterone levels.
While there are various possible reasons for this, in his book, The Male Biological Clock, urologist Harry Fisch points out that after the age of 35, men have higher rates of infertility, can contribute to the likelihood of a miscarriage, and are more likely to father a child with Down syndrome.
Just like women, men need to take care of their bodies, sooner rather than later, he says.
Making men aware that they also have a biological clock is important for shifting social attitudes but Barnes also believes the shame game stops when we no longer equate masculinity with fertility.
"One of the great puzzles of male infertility is why it continues to be shrouded in secrecy and stigma in an era when [erectile dysfunction] and Viagra are household words," she said. It was important, she added, that we raise "awareness that these issues exist, that they are medical issues, and that manly men deal with them, too."