Motherhood is a challenging role and a life-changing experience. For women living with psychiatric illness, the challenge of motherhood is amplified. Psychiatric illness (including schizophrenia, affective and personality disorders) is associated with multiple adversities that can impair the capacity to parent. Social adversity, fluctuating symptoms, and medications and their related side-effects, can create difficulties for the new mother as she adjusts to her role. The risk for relapse among women who are unwell is heightened during the post-partum period. For many other women, the post-partum period is when psychiatric symptoms emerge for the first time. Equally important are the continuing concerns pertaining to infant well-being where maternal psychiatric illness is present. For mothers who exhibit symptoms at this time, a very real threat of protective removal exists. In the mother–infant setting, child protection legislation is biased towards the rights of the child. While there are cases for which this bias is clearly appropriate, there are less clear situations from which the infant is removed with little regard for the mother. Often mothers with psychiatric illness struggle to meet the cognitive, emotional, and financial demands of drawn-out custody proceedings. For these mothers, there is a paucity of appropriate support available, as will be evidenced throughout the present paper. There is an urgent need for professional advocacy to support women who are unwell in their transition to motherhood. The mental health nurse is able to fill a key advocating role in the perinatal psychiatric setting. Nurses in this role hold a unique position whereby social and community supports can be activated, while guidance is imparted from a ground-level standpoint. The nurse in this role has the capacity to liaise with authorities, negotiate service provision, and ensure that key parenting skills are acquired by the mother as she works to secure her role. Through the provision of proactive advocacy during this time, the nurse has the potential to ameliorate the outcomes of mothers who are unable to cope alone and the well-being of their infants.