Gradually, they suspect that, like one in 10 couples, they face a problem conceiving and time is running out. As the years go by, the effects of infertility multiply. It can undermine self-esteem, destroy relationships and leave couples feeling isolated and purposeless. Ironically, it can kill interest in sex.
It is at this point that people discover how difficult it is to solve the problem. NHS fertility treatment is a lottery: getting help depends on where you live. Only about a quarter of health authorities offer a proper service. Just securing an appointment with a specialist can take years. And though the success of treatment has improved it is still low. Only one in eight women becomes pregnant after a single attempt at in- vitro fertilisation.
The potential cost could be huge were the NHS service more widely available: it costs more than £2,000 on average to assist a conception and much more for women over 35.
So we have a system that threatens to become increasingly expensive, while still being unfair. It needs overhauling in a way that is sensitive to those seeking treatment, while not diverting stretched resources from other important NHS activities.
As we report today, Labour plans, if it wins the general election, to take IVF off the NHS. This stance has certain virtues: having children is not a right and it is hard to classify infertility as an illness. More important, the move suggests that Labour accepts that the NHS cannot pay for everything, a brave step for a party that has traditionally cashed in on discontent at the level of NHS funding.
But Labour would be wrong to adopt its proposed course. Without NHS help, many couples would be too poor to rectify their infertility. The rich would still be able to go private. So the policy would replace the present chaotic provision with fresh injustice.
It is a natural and acceptable desire to want children. Within limits, a society should be prepared to help those who wish to fulfil their lives by starting a family.
Instead of supporting a blanket ban on free IVF treatment, Labour should develop a budget-capped funding system that is means-tested and consistent across the country. Every couple should be expected to pay something towards infertility treatment as a mark of their commitment to having children. But a sensitive policy should seek to ensure that cost alone does not render a couple childless.