For many women, having a child is not necessarily at the top of their priority lists. However, this may be more true for women born to mothers who are slightly older, as a new study has revealed they are less likely to have children, but we're not sure why.

A team led by Olga Basso from McGill University in Montreal, Canada, looked at the lives of over 43,000 women born in the US between 1930 and 1964. Their study, published in Human Reproduction, found that women born to mothers who had conceived after 30 were more likely to not have a child compared to daughters whose mothers had them younger. For more clarity, it was shown that 20 percent of daughters born from mothers who conceived after 30 went on to be childless, whilst 15 percent of mothers who were 20-24 and less than 13 percent of teenage mothers were the same.

Despite the strong data, the team readily admit the link between daughters of older mothers and being childless is still not clear. They didn't find fertility issues to be the cause, as neither daughters with older mothers or ones with younger ones were more likely to experience any. Basso told New Scientist that perhaps having a mother who decided to have children later “results in daughters behaving differently.”

The team also found that women who weren’t married or who had post-graduate degree were amongst the most likely to not have children, but further analysis revealed that these could not fully account for the levels of childlessness they found. 

Previous research has found that advanced degrees may play a role in why some have opted out of wanting to procreate. “The most educated women still are among the most likely never to have had a child," according to Pew Research Center. However, the team found even among women who held a postgraduate degree, those born to older mothers were still more likely to be childless.

There was also very little evidence to show that the birth of a daughter had anything to do with their father's age when it came to being childless.

Choosing to delay when to have a child as well as choosing not to have children altogether is on the rise, so the authors suggest "evaluating the influence of maternal age at birth on offspring fertility" is a public health priority.