Researchers from Bristol University, UK, found that pregnant women who experienced high levels of anxiety during the late stages of their pregnancy produced children who had higher cortisol levels when they reached the age of 10.

The researchers said many children whose mothers were stressed when they were in the womb may be more susceptible to anxiety.

You can read about this study in the journal Biological Psychiatry.

In this study, saliva samples were taken from 74 10-year old children. Samples were tested four times a day for three days (school days). The mothers filled in a questionnaire which asked them, among other things, whether they had experienced stress and/or anxiety during their pregnancy. They found that there was a clear correlation between high levels of stress during the mothers' pregnancy and high cortisol levels in the children's saliva.

The researchers pointed out that many other factors need to be taken into account when trying to ‘predict' susceptibility to depression or anxiety later in life. Such factors as the child's personality, environment, lifestyle and upbringing.

Cortisol levels can work both ways. Some mental health problems are linked to low cortisol levels.