My folks and some close friends used to tell me to try to maintain a positive, cheerful aura during pregnancy so that my baby will turn out to be a happy, contented baby too. I smiled, nodded in vague agreement, but at the end of the say, dismissed the advice as pure quack.

Turns out, they could be right. A new study indicates that a mother's emotional state during pregnancy does affect her child's cognitive development.

The authors said they found an association between "persistent depression during pregnancy and developmental delay, with a 50% increase in the odds of developmental delay associated with persistent antenatal depression". And they said the findings could better inform health workers treating pregnant women.

"These findings add to the growing body of research, suggesting that maternal psychological wellbeing during pregnancy has important consequences for child development.

If this is true, then doctors and midwives have additional jobs to do during antenatal check-ups. In addition to monitoring the baby's development and other parameters indicating the health of mother and fetus, health practitioners also need to monitor the mental state of their pregnant patients.