A massive new UN survey reveals a large gap between the number of children people want and what they end up having. The survey was conducted against a background of plunging birth rates in nearly every part of the world.

108,000 adults aged 18-39 in 73 countries responded to the online Demographic Futures Survey making it among the largest and most geographically broad surveys of its kind.

Regarding “Lifetime fertility ideals”, males report on average an ideal number of children of 2.62, compared with 2.43 among females.

However, across all regions and income groups, the number of children reported by respondents aged 35–39 is lower than the number desired by respondents aged 18–39.

Moreover, the proportion of adult respondents aged 35–39 who took part in the survey and who report having no children is 41 per cent for males and 30 per cent for females.

Among those, 79 per cent of males and 72 per cent of females would ideally like to have children.

However, separate studies suggest that at 35, just 25% of childless women will ever have children. At 40 it is just 7%.