(CNN) -- Many men might describe expecting a baby as a joyous time in their life, but for some, a bundle of joy might be linked to a greater risk of depression.
Fathers-to-be can be at risk of depression symptoms if they feel stressed or are in poor health, according to a study published in the journal JAMA Psychiatry on Wednesday. Depression symptoms may even escalate after the baby is born.
Researchers have long known about the risk of pre- and postpartum depression in mothers and the hormone changes that might contribute to their symptoms.
Now, a growing body of research sheds light on depression in fathers and the factors that might contribute to their risk of symptoms.
Turning a spotlight on paternal depression
The new study involved data on 3,523 men in New Zealand who participated in interviews while their partners were pregnant and then nine months after their child was born, in 2009 and 2010.
The participants, who were an average age of 33, were selected from a cohort whose partners were enrolled in the nation's longitudinal study titled Growing Up in New Zealand.
The fathers-to-be completed interviews intended to measure depression symptoms and answered questions about their overall health, stress and family environment.
Elevated prenatal depression symptoms were found among 82 fathers, or 2.3%, in the study, and elevated postnatal depression symptoms were found among 153, or 4.3%.
"The rates of antenatal and postnatal paternal depression that we found are consistent with previous similar studies in other countries including the US," said Lisa Underwood, a research fellow at the University of Auckland in New Zealand and lead author of the study.
The depression symptoms were associated with adverse social and relationship factors and having a history of depression, the researchers found.
"It was surprising that, for men in the Growing Up in New Zealand study, factors such as unplanned pregnancy, ethnicity and anxiety were not associated with either antenatal or postnatal paternal depression," Underwood said.
Yet, the study did have some limitations.
"We used brief screening measures to assess depression symptoms and were not able to carry out full diagnostic assessments of depression," Underwood said.
She added that since the men in the study were interviewed only during the third trimester of pregnancy and nine months after childbirth, the results might not reflect what could be found during the first and second trimesters or the period immediately following childbirth.
'Our key message applies worldwide'
All in all, the researchers wrote in their study that the new findings could help in developing screening and intervention efforts for expectant fathers.
"The lack of screening for paternal depression in New Zealand mirrors the international situation," Underwood said. "Our key message applies worldwide: Pregnancy and the postnatal period are key opportunities to engage with expectant and new fathers to discuss depression symptoms and provide support."
This isn't the first time researchers have measured depression among expectant fathers, especially new dads.
A separate study of 622 first-time dads found that 13.3% exhibited elevated levels of depressive symptoms during their partner's third trimester of pregnancy. The study was published in the American Journal of Men's Health in 2015.
Similar to the new study, that research found stress and marital relationship quality to be important determinants of paternal depression.
However, "poor sleep quality was the strongest factor associated with depression in men during their partner's third trimester of pregnancy," said Deborah Da Costa, an associate professor in the department of medicine at McGill University in Montreal, who was senior author of the earlier study.
Prenatal and postpartum depression was evident among about 10% of men in a 2010 meta-analysis published in the journal JAMA. That same paper showed that depression was relatively higher in the postpartum period.
A meta-analysis in the Journal of Affective Disorders last year found that paternal depression may be present in about 8% of men.
In the new study, the researchers wrote, "Given that paternal depression can have direct or indirect effects on children, it is important to recognize and treat symptoms among fathers early, and the first step in doing that is arguably increasing awareness among fathers about increased risks."
Sad dads can affect baby
Fathers with pre- or postnatal depression are associated with a higher risk of emotional and behavioral problems in children, especially sons, according to a 2008 study in the Journal of Child Psychology and Psychiatry.
"There are numerous ways in which a father's depression during pregnancy might impact an unborn baby," said Dr. Michael Weitzman, professor of pediatrics and environmental medicine at the New York University School of Medicine, who was not involved in the new study.
A father's depression might lead to added stress, depression or increased use of alcohol or smoking for the mother, which may influence a fetus' growth and development, Weitzman said.
Additionally, a dad-to-be experiencing depression might lead to isolation of the mother and father and might even influence the choices made in the household about prenatal care or preparation, he said.
In the new study, the researchers wrote, "Expectant fathers should seek support if they experience unemployment and/or relationship or family difficulties following the birth of their child. Men who have a history of mental health problems or who are stressed or unwell during their partner's pregnancy should be assessed for (paternal postnatal depression symptoms). Men should also be encouraged to give up smoking during their partner's pregnancy and continue not to smoke after the birth of their child."
