Childbirth is a significant life event resulting in profound and permanent changes in a woman's role and responsibilities. It is not surprising, therefore, that the perinatal period represents the time when a woman is at greatest risk for developing a psychiatric disorder. Pregnancy is not protective against mental illness and the relative risk for certain disorders increases postpartum.

Early detection and treatment are crucial in reducing morbidity and mortality for both the woman and her child. Good obstetric liaison and effective communication between all professionals are vital in preventing adverse outcomes.

The management of perinatal mental illness presents a unique set of challenges that is best provided by a specialist perinatal psychiatry service. The rationale for early detection and treatment is supported by considerable evidence highlighting the impact of untreated mental illness both on the mother and her child.

Impact of maternal mental illness

The impact of maternal mental illness on the mother and her child has been extensively studied (Brand ' Brennan, 2009) and is the rationale for early detection and treatment. There is increasing evidence linking antenatal stress, anxiety and the hypothalamic–pituitary–adrenal function in pregnancy with behavioural problems, including hyperactivity and inattention in children (Rice et al, 2007). Anxiety and depression may also be associated with obstetric complications such as low birth weight and preterm delivery.

Mental illness may interfere with a woman's ability to seek antenatal care. Commonly associated behaviours such as smoking, substance misuse, poor diet and lack of exercise further worsen obstetric outcomes.

Maternal psychotic or depressive symptoms may cause direct risks to the child ranging from neglect to infanticide. They may also cause subtle deficits in maternal behaviour such as lack of emotional warmth, unresponsiveness to the child or intrusiveness. Mother–infant attachment is often compromised (Royal College of Psychiatrists, 2000).

There is evidence to suggest that postnatal depression is associated with long-lasting cognitive, social, emotional and behavioural problems in children (Murray et al, 1996; Hay et al, 2001).