But is it something we should start thinking about earlier?
According to a new survey conducted by Red magazine, one in four women wish they had tried to start a family earlier.
The poll of more than 3,000 women aged between 28 and 45 revealed that 24 per cent regretted waiting so long to have children.
And it seems an increasing number of couples are turning to IVF in a bid to have a family.
Seventeen per cent of those asked said they were worried about being too old to conceive, and nine per cent – almost one in ten women – said they had already resorted to fertility treatment.
One in five wanted to have a child so much they said they would consider purposefully becoming a single mother, either through a sperm donor or by another route.
Just under one third said they had not met the right partner yet.
"We have identified what we call 'emotional infertility', that is being childless not by choice, due to not having a partner, to a partner not wanting to have children," Brigid Moss, health director of the magazine said.
"It's become more acceptable to talk about medical infertility with your friends and family, so woman can now be more open about that," she added.
"Every few months, there's another warning from the medical profession that the best time to conceive is under 35.
"But this report has shown that often at the right biological time, women are simply not in the right place emotionally or financially to start trying."
All the news as Duchess Kate's due date draws close...