In a study by researchers at Johns Hopkins University in Maryland showed that stress during pregnancy inhibits neural growth.

For the research, the team led by Janet DiPietro examined 112 healthy pregnant women three times during their third trimester and asked them about their stress levels, Child Development journal reported.

They first recorded foetal movements and then examined the babies two weeks after birth. Their observation showed that women who reported higher stress levels during pregnancy had babies that moved around more in the womb.

After birth, these babies scored higher on a brain maturation test, although they were more irritable. More active foetuses had better control of body movements after birth.

"The stress hormone cortisol plays a role in brain maturation, which may help explain the result, DiPietro said.