A recent study by British researchers once again emphasized the importance of peaceful and stress-free pregnancy.

The study indicated that stress during pregnancy can lead to behavioral and emotional problems in the child.

The research team found that stress caused by violent or abusive relationships with the partner has an adverse effect on the development of a baby's brain.

The study indicated that the stress hormone cortisol affects the baby in the womb. Normally, the placenta acts as a barrier; but in the case of a stressed mother the placenta is less protective and the mother's cortisol may have an effect on the foetus.

The placenta protects the unborn baby from the mother's cortisol, by producing an enzyme that breaks the hormone down. During stress, the mother loses her ability to produce this enzyme, which means her own stress hormones can pass into the body of her baby.

The research team found that higher the level of cortisol in the womb, the lower the toddler's cognitive development - or "baby IQ" - at 18 months. Lead researcher, Professor Vivette Glover, from the Institute of Reproductive and Developmental Biology at Imperial College London, said: "We all know that if a mother smokes or drinks a lot of alcohol while pregnant it can affect her foetus. Our work has shown that other more subtle factors, such as her emotional state, can also have long-term effects on her child."