New York, Sep 18 (IANS): Experiencing the death of a family member within six months before conception may decrease the chance of offspring's survival, new research has found.

"Our findings suggest that the six-month period prior to pregnancy may be a sensitive developmental period with implications for early offspring mortality," said the study led by Quetzal Class, postdoctoral researcher at University of Chicago in the US.

In contrast, maternal bereavement during pregnancy does not affect the infant mortality rate, the findings showed.

"Bereavement is a major life stressor from both a psychological and physiological perspective," Class noted.

Grieving may lead to changes in the maternal stress system affecting offspring development--particularly during the vulnerable period of early organ development--or alter the mother's biological preparedness for pregnancy, the study explained.

The researchers analysed data from all women who gave birth in Denmark between 1979 and 2009.

Infant and child mortality rates were compared for women with and without "maternal bereavement"--defined as the death of a parent, sibling, or previously born child--in the months before conception or during pregnancy.

The analysis included data on nearly 1.9 million singleton births.

The results showed increased mortality for infants born to mothers who experienced the death of a family member in the months before conception.

After adjustment for other factors, risk of infant death during the newborn period (before one month) was more than 80 percent higher for women with preconception bereavement.

For infant death between one month and one year, risk was about 50 percent higher for women with bereavement before conception.

The study appeared in the journal Psychosomatic Medicine: Journal of Biobehavioral Medicine.