Depression has long been known to affect some mothers after the birth of a child.
But now, new University of Otago (Christchurch) research has found that like mothers, fathers may also experience the "baby blues".
Now the researchers are recommending doctors and health professionals consider assessing both new mothers and fathers for depressive symptoms.
University health and development study researcher Dr Geri McLeod said the study showed major depression was experienced by one in five new dads aged 17-18, and one in three new dads aged 20-21.
Overall, 5.4% of fathers were affected by major depression.
"The highest prevalence of major depression occurred among fathers younger than 30 years. No fathers aged 34 or over were classified as having major depression."
Paternal depression was a growing global health concern because the mental health of fathers affected the psychological, physical and mental health of the developing child, Dr McLeod said.
"Fathers can experience depressed mood, worry, loss of interest, social withdrawal and role confusion as they transition into fatherhood.
"Paternal depression is a form of distress potentially compromising the daily care of a child."
Associations may also exist between depression in fathers and later emotional and behavioural problems, and subsequent psychopathology.
"Furthermore, as family dynamics change, and fathers take on the role of primary caregiver, the impact of paternal depression on both the child and the family needs to be considered."
The study was based on men who were participants in the Christchurch Health and Development Study (CHDS).
Data was gathered using a combination of sources including parental interviews, interviews with the cohort member, teacher reports, standardised testing and medical and other official records.
Previous literature had a greater focus on mothers because they were most often the main caregiver, she said.
"However, an increasing number of fathers are taking on the role of primary caregiver.
"This study has shown that younger fathers may be at greater risk of experiencing major depression.
"Research into paternal depression is important — not only for the father, but also the family — because of the impacts on the developing child and the relationship with the other parent."
Clinicians should consider assessing both new mothers and fathers for depressive symptomology, she said.
"This will ensure adverse outcomes of parental depression will be minimised through the provision of timely support to those who need it."
