L

arissa Hazell is passionate about children. She was a full-time nanny for 15 years, working 60-hour weeks before her son was born three years ago, and has now set up a company helping parents to find childcare.

But she has made the decision to not have any more children. “My husband and I are priced out of having a bigger family, we just couldn’t afford it,” Hazell, 33, said.

They are not unique. Last year there were some 3.7 million families with only one dependent child — 14 per cent up on the 3.2 million in 2004, according to the Office for National Statistics.

One-child families are becoming more common; in some cases parents simply choose to have a smaller family, but many others are being priced out of having more children. A study by University College London last year found that two fifths of 32-year-olds in England wanted children, or more children, but just a quarter were actually trying to conceive — affordability pressures and career concerns were among the biggest reasons for the delay.