With the average age of first-time mothers on the rise (it has increased from 24.5 to 28.1 since 1980 in the UK), researchers have made a shocking discovery about women waiting till their 40s to start a family.
A London School of Economics research found women who wait till their 40s to have a baby are more likely to give birth to overweight and less intelligent babies.
According to the study published in the journal Biodemography and Social Biology, children born to mothers in their 30s are more likely to be the smartest in their class.
The researchers also found children born to women aged 23-29 are less likely to be as clever as children born to women aged 30-39.
The researchers analysed 18,000 births in the UK.
The study author, Alice Goisis, in a report by The Times said that first-time mothers in their 30s are, for example, likely to be more educated, have higher income, more likely to be in stable relationships, have healthier lifestyles, seek prenatal care earlier and have planned pregnancies.