Putting off having that baby? It’s in your genes

CLASS – and not education – is the main driver for British women delaying motherhood, a study has found.

It had been widely assumed a woman’s desire to go to university or college before starting a family was the reason women postponed motherhood.

But researchers found that education played a much smaller role than previously thought and a woman’s family background was the major factor.

Since the end of the Second World War, the average age of first-time mothers has increased by four to five years throughout Europe and the United States.

The study by the University of Oxford and the Universities of Groningen and Wageningen in the Netherin lands found educational attainment for women also increased over the same period.

The average age of women when they left education rose steadily throughout the 20th century, but the age of first-time mothers did not follow the same pattern – instead forming a U-shape.

New mothers were still relatively young after the war during the socalled ‘baby boom’ but were also generally becoming more highly educated. Only from the 1960s did women start to delay motherhood, which coincided with the introduction of the Pill.

Those born after the 1960s postponed motherhood by around 2.7 years, on average, compared with women born at the end of the Second World War. But researchers said longer educational enrolment accounted for only 6 per cent of this delay.

Using data from the Office for National Statistics on women born the UK between 1944 and 1967, the scientists tracked patterns of educational enrolment to see how they influenced reproductive behaviour.

They also compared the fertility histories of more than 2,700 female twins from the largest adult twin register in the UK.

This acted as a controlled trial because this isolates the effects of different levels of education between siblings in pairs of twins who share so many other characteristics.

Their model calculated that for every extra year of educational enrolment after the age of 12, a woman delayed motherhood by an average of six months.

But strikingly, they also found the main influence on whether a woman postponed having children was largely associated with her family background. They concluded family environment – a combination of a woman’s social, economic and genetic factors – was significant.

Education alone contributed to only 1.5 months of the total sixmonth delay.

Lead author Dr Felix Tropf, from the department of sociology at the University of Oxford, said: ‘Our research casts doubt on previous studies that claim a strong link between educational expansion for women and the postponement of motherhood. We find that both education and a woman’s fertility choices seem to be mostly influenced by her family background.

‘For example, families provide social and financial support, and pass on genes affecting reproductive behaviour. A large part of the observed association between education and age at first birth in other studies can actually be explained by the family environment. In isolation, education has a much smaller effect.

‘We hope this important finding may inform those forecasting future fertility trends or shaping family policy.’ The study was published in the journal Demography.

‘Influenced by her background’