A researcher at the University of Lethbridge says the cause of premature births could be linked back to stress in past generations.

This research could help understand Alberta's pre-term birth rate, which is the highest in Canada.

Researchers subjected rats to stress late in pregnancy and observed their offspring. They found that the daughters of stressed rats had shorter pregnancies than the daughters of rats not subjected to stress, and that the granddaughters of stressed rats also showed shorter pregnancies even if their mothers had not been stressed.

"I think if you understand the mechanisms of how this is being generated — the footprint of stress — we have a means of predicting the risk of pre-term birth in future generations and finding certain interventions," said Gerlinde Metz,  a professor of neuroscience and Alberta Heritage Foundation Medical Senior Scholar at the university and one of the researchers on the team.

Metz says stress can alter the genes, meaning mothers-to-be can pass the altered genes on to their babies and that's why the future generations showed the effects of the original rat's stress.

The study looked at four generations of maternally-related rats.

It found the stressed rats and their offspring also gained less weight during pregnancy and had higher blood glucose levels.

As well, their offspring were smaller and had delays in behavioural development, all effects which were amplified over successive generations.

Metz says the study could help provide clues to the causes of pre-term births in humans as well as help other researchers identify the predictors and possible interventions for the pre-term births.