10/09/2014 13:29 BST | Updated 10/11/2014 05:59 GMT

Postnatal Depression in Fathers - Five Things You Need to Know

Postnatal depression in fathers does exist. There are many factors, both situational and physiological, which can affect a father's mood both before and after a baby is born, and yet it's an area of parenting which is often ignored or overlooked by healthcare professionals and parents alike. While writing a book on PND in fathers I spent many months researching the condition and talking to all those involved with it - sufferers, academics and experts - here are five important things I found out.

1. It's difficult to diagnose.

Depression is often less apparent in men than it is in women. Depressed men tend to change their behaviour, often becoming cynical, indecisive, angry, or avoiding social situations. Sometimes they start drinking too much, or working too hard, some have affairs or start even more extreme and risky behaviour. Of course there can be many different causes for all this sort of behaviour, but it is important to remember that depression, including postnatal depression, can be one of them.

Let's not forget, either, that disturbed sleep, lack of energy, loss of appetite and even feelings of guilt are all part and parcel of caring for a new baby. They can also be symptoms of depression in both mothers and fathers, and every sufferer will experience it's can be difficult to diagnose PND in any parent.

2. Fathers experience hormonal changes around the time of childbirth too.

Hormonal changes in new mothers are well-documented, but a new father's hormones will be changing too. Levels of testosterone decrease when a man's partner is pregnant and just after she's given birth - while it is thought that this increases a father's sensitivity to his child's needs, it can also be a sign of depression. Cortisol, the 'stress' hormone increases in the run up to childbirth, and then drops immediately afterwards - hormonal dysregulation can have a negative affect and some fathers will notice it more than others. Other hormones, such as oestrogen, prolactin and vasopression can all make a father feel different after the birth - and not all in a good way.

3. Fathers can feel jealous of their new baby.

Sometimes, a father can feel like their baby is replacing them in their relationship with their partner. New babies are hard work, and they completely take over a parent's affections and attention - usually a mother will be entirely taken over, both physically and emotionally by their child after it has been born. Fathers can feel pushed out, jealous of the close connection their partner has with the baby, and this can sometimes, in some men, trigger depression.

4. Some people think that men shouldn't be at the birth of their baby.

There are a growing number of professionals who think there is a link between postnatal depression and a man's presence at the birth of his child. Certainly, a traumatic birth can trigger depression in both mothers and fathers, but sometimes even a straightforward birth can be too much for a father to witness. It might be time, for some couples, to return to the old-fashioned idea that childbirth is strictly women's business.

5. Postnatal depression can affect same-sex couples too.

Fathers are often less prepared for parenthood than mothers, who have grown up with a certain expectation that they will one day fulfil their feminine purpose and have children. Fathers can sometimes have less ability or opportunity to imagine parenthood, and so in families where there are two fathers, the shock of becoming parents is compounded and can morph into depression. The stress of parenting can affect any parent, and same-sex couples are not exempt from the postnatal depression just because they don't fit the traditional model of a family.