While both mothers and fathers can suffer equally from postpartum depression (PPD), most people only recognise it in women. A recent survey of 406 British adults suggests that men remain largely 'invisible' when it comes to public perceptions of depression following childbirth.

In fact, the online respondents were almost twice as likely to identify signs of depression in new mothers as they were in new fathers.

Until now, only a handful of studies have examined how the public regards PPD, and most of these have been focused on maternal cases. While the new study is relatively small and limited in scope, it reveals how the scientific and medical bias around paternal PPD can also extend to the public.

Though rates may vary, the prevalence of maternal PPD is between 6 to 13 percent. For paternal cases, it's more like 8 to 11 percent. Despite how similar these ranges are, new fathers are frequently under-diagnosed and untreated for mental health problems after the birth of their child.

Gender constructs, the authors argue, are at least partly to blame. While many modern societies regard men as tough, stoic, and self-reliant, women are more likely to be considered fragile and vulnerable.

The results of the study are a good example of how gender constructs can influence our perception of suffering. Participants were first presented with case studies of either maternal or paternal PPD, and then asked if they believed "anything was wrong" (yes or no).

No matter the sex of the respondent, they were less likely to say that there was something wrong with the male (76 percent of responses) than the female (97 percent).

"More specifically, we found that participants reported significantly lower perceived distress vis-à-vis the male target's condition, believed that the male target's condition would be easier to treat, expressed less sympathy for the male target, and were less likely to suggest that the male target seek help," the authors write.

This isn't to suggest the participants were being unnecessarily cruel or careless: it appears they genuinely thought the men were suffering from something else. When asked what that might be, many suggested stress or tiredness.

Yet despite the case studies presenting identical symptoms for both men and women, stress was suggested as problem 21 percent of the time for men but only 0.5 percent for the woman. (If someone answered 'baby blues', their answer was deemed incorrect, as this is considered a mild mood swing not associated with PPD.)

"These findings suggest that our participants may have been less likely to view the difficulties faced by the male target as one of mental ill-health and more likely to emphasise factors that are common to most new parents (eg. a lack of sleep)," explain the authors.

There may be a number of reasons for these results, the authors admit, all of which are outside the scope of this study. For instance, the authors suggest that many think men are immune to PPD because they do not fall pregnant or experience pregnancy-induced hormonal changes, delivery complications, or the difficulties of breastfeeding.

Lead author Viren Swami, a research psychologist from Anglia Ruskin University in the UK, says he was himself unaware of the problem before he was diagnosed with the disorder after the birth of his son. He told Reuters he was determined to figure out why so many others think the same way.

While the wider medical community is slowly changing its attitudes towards paternal PPD, Swami thinks there's lots of scope to increase awareness among the public – many of whom, as new fathers, may not be receiving help they might need.

"What is clear is that much more can be done to promote better understanding of paternal postnatal depression, so people don't brush it off as simply tiredness or stress," says Swami.

"This is particularly important as many men who experience symptoms of depression following the birth of their child may not be confident about asking for help and may be missed by healthcare professionals in the routine assessments of new parents."

The research was published in the Journal of Mental Health.