Nurses trained to assess and psychologically support new mothers can prevent the onset of postnatal depression, according to a new study in England.

Postnatal depression, also called postpartum depression, is a serious condition that affects between 8 percent and 20 percent of women after pregnancy, according to the National Institutes of Health.

The study is the first large-scale randomized trial to clearly show a significant reduction in future cases of depression, according to the researchers. The analysis was based on women who were not depressed when they joined the study, and who were randomly selected from a larger sample.

"Up until now, it was thought that depression could only be treated when it is picked up by a general practitioner or health visitor," study researcher Terry Brugha, of the department of health sciences at the University of Leicester in England, said in a statement. In the National Health System in the United Kingdom, so-called health visitors are registered nurses who may visit homes and who have specialized training in child health, health promotion and health education.

"But this study shows that women are less likely to become depressed in the year after childbirth if they are attended by an NHS health visitor who has undergone additional training in specific mental health assessment and in psychological approaches based on either cognitive behavioral or listening techniques," Brugha said.

Women who had a health visitor with additional mental health training were 30-percent less likely to have developed depression six months after giving birth compared with women receiving usual care, according to the study, which is published in the current issue of the journal Psychological Medicine.

The results also suggest that these improvements continued throughout the 18-month follow-up. In discussing the findings, the investigators considered that the quality of the ongoing relationship between the health visitor and mother.

Brugha determined that, in instances where the relationship between the nurse and the mother continued until the child started to attend school, the nurse likely provided the mother with a reliable confidant to turn to if necessary.

In addition, these mothers may have benefited from knowing they didn't have to discuss emotional concerns with relative strangers, such as a doctor or psychologist, and that access to help would be easy and non-stigmatizing, according to the findings.

The study involved analyzing data previously collected as part of a clinical trial designed to test the effectiveness of health visitors in identifying and managing postnatal depression following childbirth.