Researchers have linked
stress experienced by pregnant women to higher incidences of mental and
behavioural problems in their children.
The research, presented yesterday
at a Royal College of Psychiatrists conference in London, suggests high levels
of the stress hormone cortisol in amniotic fluid in the womb could affect the
development of the brains of foetuses, affecting their future social skills,
language ability and memory.
Vivette Glover, of Imperial
College London, said there was now reason to believe that 15% of the 1m
diagnoses of ADHD, cognitive delay and anxiety in children could be due to the
stress experienced by their mothers during pregnancy.
She told the conference:
"We found that if the woman had a partner who was being emotionally cruel
to them while they were pregnant it had a significant effect on their baby's
development. It shows that the partner has a big role to play."
The researchers followed 125
women who were having amniocentesis - samples of amniotic fluid taken from the
womb - for other medical reasons and used samples from the test to measure
their cortisol levels. They conducted stress analysis of the women before and
after birth, then tested their babies at 18 months.
They found that those who
experienced stressful events during pregnancy had lower mental development
scores independently of what had happened to them after they were born. Serious
conflicts with partners, including domestic violence, were the biggest causes
of stress.
"These babies
performing worse on development scores were exposed to high level of cortisol
in the womb," said Kristin Bergman, the lead Imperial researcher on the
paper.
Previous research has linked
mothers' stress levels to their future child's mental health and cognitive
ability but this is the first to make the cortisol link, and there have also
been conflicting findings. Last year, American scientists reported that
moderate levels of stress were linked to more advanced mental ability in
children by the age of two.
Criticisms surround the area
of research because it is hard to blame the exposure in the womb to stress
while ruling out that the babies' social environment after birth has an effect.
The researchers behind this study say they have identified cortisol as a cause,
ruling out the possibility that environmental factors after the baby was born
had an effect.
Ms Bergman said: "This
should not immediately worry women who are expecting a baby, but it has a
number of implications for health strategies. We believe this is proof of a
convincing argument for screening all mothers for stress during
pregnancy." The findings of the research are being submitted for peer
review and publication.