Factors that can increase your risk of experiencing postnatal depression include having: a family history of depression or postnatal depression (genetics appears to play a role in both of these conditions but exactly how is still unclear) previously experiencing depression, postnatal depression or other mood disorders The role of hormones It was once thought that huge changes in hormone levels during and after pregnancy were the sole cause of postnatal depression. This is no longer thought to be the case, although changes in hormone levels may still play a part. One theory is that some women are more sensitive to the effects of falling hormone levels after they’ve given birth. All mothers will experience hormonal changes but only some mothers will be affected emotionally. It’s possible that this, as well as the stress of looking after a baby or money problems, may trigger the depression.