The exact cause of postnatal depression is not known. Research suggests that there are some factors that contribute to it.
If you have a history of depression, this can be a risk factor for postnatal depression.
It is possible to experience anxiety at the same time as postnatal depression.
A small number of women who develop postnatal depression have a temporary thyroid gland defect. This is linked to mood changes.
Some women may be particularly vulnerable to the drop in hormones that happens after giving birth. There is no firm scientific evidence to support this, but there is ongoing research on the subject.
Changes in lifestyle
The birth of a baby brings changes to your life. New babies are hard work. You are dealing with the constant demands of feeding, bathing, crying and putting your baby to sleep. This usually means you lose a lot of sleep.
You lose the freedom you enjoyed before your baby arrived. This sense of loss can contribute to depression.
It may take time for you to find ways to adjust to your changed circumstances.
Strain on relationships
The birth of a baby can also have a huge impact on your relationships with your partner, family and friends. This can sometimes cause enormous strain.
Stressful life events
Recent life events, such as bereavement or serious illness, may mean that you were stressed before the birth of your baby. You may also be stressed because of unemployment or lack of money.
You may be more likely to suffer depression after having a baby if you do not have support from your partner or family.
Images of motherhood
Media and online images can make you feel that new mothers should be attractive, energetic and live in a perfect home with a supportive partner.
Many women think mothering is instinctive, not a skill you need to learn. If you find the weeks and months after childbirth difficult, you may feel that you are the only one not coping. This can lead to overwhelming feelings of failure and isolation.
If you are feeling overwhelmed, it is important to talk to someone. This could be a family member, close friend or your GP or public health nurse.