During the perinatal period, women may experience severe mental health problems. Research has shown the potential negative impact of mother-baby's separation and of parental psychiatric illness, on the child. MBUs care requires different staff's expertise in order to: treat women with psychiatric disorders, ensure child care and development, and support appropriate mother–infant interaction with “good enough” mothering. For this, a multidisciplinary team is needed. Specific attention is also given to the child's father. Most MBUs may admit women with infants from birth till one year old and during several weeks or months.

More than two third of admitted women are discharged either symptom-free or greatly improved. An efficient follow up at discharge should be prepared with the women, the child's father, when presents, and linked to familial, social and medical resources. Moreover, MBUs staff should collaborate with other psychiatrists, obstetricians, midwives, pediatricians, and social workers. Mother–baby units should be part of a local health perinatal network including maternity unit, neonatal care, and community resources.

Referral for admission in MBUs may be required for women with a first acute episode, or a relapse, of a severe psychiatric disorder such as postpartum psychosis, manic disorder, major depressive episodes, schizophrenia, personality or behavior disorders. Moreover for prevention purposes, referral of women with known chronic mental health problems may start already during pregnancy.

Challenge of benefice and limit of MBUs’ care will be discussed with participants.