So often we are told that women who regret their childlessness only have themselves to blame - that they are too career-focused or unrealistic about the perimeters of their own fertility. But it's a lazy stereotype - and an unfair one.
What about men in this equation? In my many years working as a consultant in reproductive medicine I've seen women in their late 30s or 40s who may have longed for a baby for years; but it is their partners who've delayed matters.
Both genders are subjected to the all-too encouraging examples of famous men and women who've become mothers in their 40s and fathers in their 60s - yet the glossy magazines don't tell you that often these parents undergo many rounds of IVF or use donor eggs or sperm. These examples can cause both men and women to think they have all the time in the world, even if their partner thinks differently.
I've seen many happy relationships put under unbearable strain when partners' 'fertility clocks' are out of synch, through the stress of IVF and the pain of disappointment. The tragedy is, it's so easily preventable. For while men know women have a 'biological clock', some are unaware of how steeply female fertility declines after the age of 35. Many men also fail to realise that their own fertility has an age-related decline: from the age of 40 there can be a reduction in the quality of sperm that can make it harder to conceive.
That's why I was surprised to hear Professor Adam Balen of the British Fertility Society saying recently that girls as young as nine should be advised not to leave it too long to start a family. I believe fifteen is a more mature age to start fertility education and we should also teach boys.
In today's modern age not all families are comprised of a man and a woman, and there are a number of women who may choose to embrace motherhood alone. However when a man and woman decide to embark on parenthood, it should be a joint decision and joint responsibility.
Therefore, both girls and boys need to have the right information to be able to make a responsible decision, to give them the best possible chance of having a healthy family when they're ready.
And there are many important messages that we need to get through to boys. Their own biological clock is discussed less, I think, because it starts a bit later and because men make sperm all their lives so can potentially remain fertile for longer - whereas women are born with a finite number of eggs.
But delaying fatherhood can increase the risk of having a child with autism and ADHD (attention-deficit hyperactivity disorder) particularly after the age of 45 if the sperm quality is reduced. That's why it's so important for men to be educated about the effect of their age on fertility. Boys also have to be taught that alcohol, drugs, smoking, obesity and occupational hazards like working with pesticides can all compromise their fertility, too.
They should know that fertility varies according to the woman - you can't make assumptions your wife or partner will be fertile into her early 40s. For example, if her mother had an early menopause, she might too.
On average one in seven couples have fertility problems and this rises to one in three when the woman passes 35 (and two in three if she's over 40). This is not about saying men are in any way responsible, but rather about making sure that both men and women know that if you want children then you need to ensure you have all the information and do not involuntarily leave it too late.
By ensuring that both young men and women properly understand how their fertility changes over time, we can help avoid a situation where couples and women come to fertility clinics looking for help to conceive simply because they have missed their fertility window.
I've become so concerned by the situation that last year I wrote to Nicky Morgan, former education secretary, about the need to include fertility education in the curriculum.
I have subsequently met with head teachers and developed fertility modules already being taught in two schools - with plans to roll it out further.
It's really unfair to make fertility only a woman's issue. Women are trying to do their best - they should be able to have everything they dream of in their lives. To be able to have a successful career and a family if they wish. For that to happen both men and women have to own up to that responsibility. Starting a family is very much a personal choice but it's a choice that both men and women have to make.
And that's why it's so vital we educate boys as well as girls about their fertility.Suggest a correction