Men and women not only see things differently, but also their reaction to conflict in a relationship differs.

Researchers from Pennsylvania State University, observed 138 couples who were expecting their first child. Both sexes separately completed questionnaires regarding their relationship experiences and individual qualities, attitudes and well-being. Researchers also recorded two six-minute interactions of each couple discussing something not related to their relationship. They were then instructed to discuss three problems in their relationships.

Following the interviews researchers collected saliva samples of the participants. The saliva was used to measure the amount of cortisol, a hormone that is released in response to stress, within the saliva. Samples of individuals' salvia were collected during interviews, following the conflict and then again 20 minute following the second sample.

The study revealed men's increased stressed levels depend on the level of hostility the couple has expressed, indicating greater physiological stress. Conversely, the same pattern was not found for women. Researchers theorize during pregnancy women's cortisol levels are already high during pregnancy.

"It is especially important to understand how relationship conflict may affect stress during pregnancy, as maternal stress has been linked to health problems for both the mother and child. And men who have difficulty dealing with stress could end up reacting angrily to future disagreements, which could affect the quality of the relationship, parent-child relations and children's adjustment, "said Mark Feinberg, research professor in the Prevention Research Center for the Promotion of Human Development at Penn State

Additionally, researchers observed men with high level of stress and anxiety recovered less, while women with high anxiety recovered more.

"For generally anxious men, more expressed hostility was also linked to more persistence of this elevated stress. On the other hand, generally anxious women experienced relatively more prolonged stress when there were lower levels of negativity and hostility expressed during the discussion. We speculate that these anxious women, as well as women in relationships in which chronic arguing is a feature, find the airing of differences, even when the tone turns negative, to be reassuring that the couple is engaged with each other," Feinberg said.

This study will be published in the British Journal of Psychology.