The new study suggests depression in dads-to-be can increase risks of preterm birth in their babies, prompting researchers to call for proactive approaches targeting expectant dads.
The study, published in BJOG: an International Journal of Obstetrics and Gynaecology, is led by Prof. Anders Hjern, from the Centre for Health Equity Studies in Sweden.
During pregnancy, depression in women has previously been linked with low birth weight and increased risk of premature birth.
Preterm birth, which can be classified as very preterm (less than 32 weeks' gestation) and moderately preterm (32-36 weeks' gestation), is a major cause of infant mortality in high- and middle-income countries.
According to the World Health Organization (WHO), it causes long-term health consequences for survivors, including learning disabilities and visual and hearing problems. Furthermore, it is the leading cause of death worldwide in children under the age of 5.
Although maternal stress has been put forward by previous research as a risk factor for preterm birth, the findings have been inconsistent and varied by sample size and stress measurement methods.
Larger, population-based studies with objective stress measures have yielded more consistent links, but the researchers say they have been limited to using a single stressful life event as an indicator of maternal prenatal stress.
Depression in partner 'can be source of stress for expectant moms'
To get around some of the limitations previous studies have faced, Prof. Hjern and colleagues defined depression in their study subjects as having had an antidepressant prescription, or receiving outpatient/inpatient hospital care, from 12 months before conception to the end of the second trimester.
The team assessed more than 350,000 births in Sweden from 2007-2012 and investigated parental depression - in both mothers and fathers - and either very preterm birth or moderately preterm birth.
Those who had depression were classified as "new" cases if they had not had depression in the 12 months preceding diagnosis. All other cases were defined as "recurrent" depression.
Results showed that new and recurrent depression in the mothers was linked to a 30-40% increased risk of moderately preterm birth. Meanwhile, new depression in the fathers was linked to a 38% increased risk of very preterm birth.
Interestingly, there was no link whatsoever between recurrent depression in the fathers and preterm birth - so only new depression in fathers increased risks.
Prof. Hjern explains that depression in a partner can be a source of stress for expectant mothers. As such, "this may result in the increased risk of very preterm birth seen in our study." He adds:
"Paternal depression is also known to affect sperm quality, have epigenetic effects on the DNA of the baby, and can also affect placenta function. However, this risk seems to be reduced for recurrent paternal depression, indicating that perhaps treatment for the depression reduces the risk of preterm birth."
Perhaps unsurprisingly, depression in mothers increased preterm birth risks, "regardless of whether the depression was new or recurrent."
'Proactive approach targeting expectant fathers may be beneficial'
The study benefits from a large sample size, but the researchers say there are some limitations. Firstly, they note that gender differences in mental health service usage could affect "the sensitivities of the exposure measurement" between mothers and fathers.
Additionally, the study's definitions of new and recurrent depression do not translate into these exact definitions in a real-world clinical psychiatric setting. However, the study's design "only allows for the identification of previous episodes during a short period of time."
The researchers add that future studies with validated depression measures should be conducted in order to confirm the links.
They conclude their study by noting that depression in the father could limit the emotional support that the mother receives, having a negative effect on the mother and, potentially, the fetus. They add:
"In addition to emotional withdrawal, depressed mood and lack of energy, men's depressive symptomatology more often includes high levels of irritability and anger, compared with depression in women, which may be perceived as particularly stressful for the expectant mother."
Prof. Hjern concludes that "since men are less likely to seek professional help for any mental health problems, a proactive approach towards targeting the well-being of expectant fathers may be beneficial."
Medical News Today recently reported on a study that suggested childhood poverty is linked to brain changes related to depression.