The current classifications of maternal filicide have relied on categories based on the immediate antecedents or motivations to the impulse to kill. The most useful outcome of these approaches has been to specify that the group that kills newborns differs from other groups in terms of their age, demography, relationship profile, and motivation. The remaining groups are diverse and overlapping. Common themes in these five cases included mental illness, vulnerability factors, social isolation, and difficulty in forming successful relationships. Findings indicated that developing an understanding that has clinical relevance and may be useful in risk assessment requires examination of a range of factors, including mental state, relationship factors, and the impact of developmental experience. Tables and 20 references (Author abstract modified)