Moms who delay pregnancy get smarter, healthier kids: Study

The team from Max Planck Institute for Demographic Research in Rostock, Germany, found that mothers who delayed childbearing to older ages -- even as old as 40 or older -- had children who were taller, had better grades in high school and were more likely to go to university.

The team analysed over 1.5 million participants -- born between 1960 and 1991 -- to examine the relationship between maternal age at the time of birth and height, physical fitness, grades in high school and educational attainment of the children. 

They compared siblings who share the same biological mother and father. 

The findings, published in the journal Population and Development Review, indicate that due to urbanisation of countries -- educational opportunities are increasing and people are getting healthier and, in other words, it pays off to be born later.

For instance, a woman born in 1950 who had a child at age 20 would have given birth in 1970. If that same woman had a child at 40, she would have given birth in 1990. 

The child born in 1990, had a much higher probability of going to a college or university than somebody born 20 years earlier. "Those 20 years make a huge difference," said lead study author Mikko Myrskyla.

Despite the risks associated with childbearing at older ages, which are attributable to ageing of the reproductive system, these risks are either counterbalanced or outweighed by the positive changes to the environment in the period during which the mother delayed her childbearing, the authors stated.

"By comparing siblings who grew up in the same family it was possible for us to pinpoint the importance of maternal age at the time of birth independent of the influence of other factors that might bias the results," said co-author Kieron Barclay from London School of Economics.