Child Murder by Mothers: A Critical Analysis of the Current State of Knowledge and a Research Agenda

The analyses were based on extensive database searches, including searches through PubMed (Medline), PsychINFO, the Psychology and Behavioral Sciences Collection, and Sociological Abstracts. Search terms included “filicide,” “infanticide,” “neonaticide,” and “fatal child maltreatment.”

All 39 studies we reviewed were retrospective in design. Ten included retrospective interviewing of mothers. Twenty-six included a comparison group. Many of the studies included intragroup comparisons.

Of the 39 studies specifically reporting on maternal child homicide, 13 were conducted in the United States and 26 were conducted in other countries. Thirteen other nations were represented: Canada (five studies), nations within the United Kingdom (five studies), Australia (four studies), Finland (three studies), Japan (three studies), with one study each conducted in Austria, Brazil, Hong Kong, New Zealand, Sweden, and Turkey. Four U.S. studies addressed neonaticide; three analyzed data from samples of administrative records, and one analyzed data from a psychiatric population (Table 1). Of the studies conducted outside of the United States, 11 addressed neonaticide; seven of those studies were based on administrative records, three examined data from psychiatric populations (either hospitalized or psychiatrically evaluated women), and one analyzed data from a correctional population. With regard to maternal infanticide (maternal filicide within the first 12 months of life, often defined by statute in countries outside the United States), one study of an administrative records sample was conducted in the United States and five were done in other countries.Studies of maternal filicide had various inclusion criteria for the child’s age. Many studies combined analysis of neonaticide with that of other filicides. Ten such studies of maternal filicide were conducted within the United States: two with administrative records, five in psychiatric populations, and three in correctional populations. Nineteen such studies were conducted outside the United States: 10 with administrative records, seven in psychiatric populations, and two in correctional populations.

We found that the research on child murder by mothers, especially within the United States, was sparse. Studies of neonaticide that used administrative records samples and correctional populations both inside and outside the United States had fairly consistent findings. They frequently showed a pattern of powerlessness, poverty, and alienation in the lives of the women studied. However, the common factors, such as being young, poor, and undereducated and living with one’s parents, describe a huge segment of the female population. There were virtually no distinguishing features to suggest which young, poor, and undereducated women with poor prenatal care were at risk for neonaticide. It is not surprising that the samples of neonaticide offenders from psychiatric populations differed from those in administrative records samples regarding the presence of mental illness, but data on this characteristic were sparse, and the results differed across countries.

Some of these studies noted that women who committed neonaticide had a high probability of denying or concealing their pregnancy. Denial or concealment of pregnancy may indeed be a predictor of neonaticide, but such behavior would be difficult to identify prospectively. The lack of prenatal care may also be a valid predictor of neonaticide. Additional, careful study is needed to elucidate factors related to denial of pregnancy in women who receive no prenatal care.

Knowledge about maternal filicide after the first day of life is even more meager. Offenders in psychiatric populations in the United States and other nations had high rates of previous mental health services use, depression, suicidality, and psychosis, as expected of psychiatric patients. Studies of maternal filicide in corrections populations noted social disadvantage in offenders. Studies conducted outside of the United States documented more mental illness in offenders.

England’s Infanticide Act, the modern version of which became law in 1938, was based on the concepts of puerperal and lactational insanity (18). The Act reduced the charge from murder to manslaughter for a woman who killed her infant under age 1 year if “the balance of her mind was disturbed by reason of her not having fully recovered from the effect of giving birth to a child or by reason of the effect of lactation” (100). More than 20 countries currently have such legislation, including Canada and much of Australia, but not the United States (18). In these countries, infanticide laws often result in the woman’s receiving probation or referral to mental health treatment rather than incarceration (18). It is noteworthy that such legislation does not require that the mother have a formally diagnosable mental illness. Therefore, a nondepressed and nonpsychotic mother who commits neonaticide may be shown greater lenience than a psychotic and depressed mother who kills her 13-month-old child. Many severely mentally ill mothers may not be considered under legislation that applies only to death of children under age 1 year; a recent study found that the mean age of child victims of mothers found not guilty by reason of insanity in two states was older than 3 years (101). We would expect findings to be somewhat skewed when considering study results from various countries. However, samples in these studies often included mothers who killed children older than age 1 year. Specifically, one might expect that women in the United States who successfully plead insanity and procure a psychiatric disposition would be more psychiatrically ill than those with a psychiatric disposition in countries with infanticide laws. Likewise, women who had criminal dispositions in countries with infanticide laws might be less likely to be mentally ill. However, other things being equal, results from the more general administrative records samples may be similar.

Maternal filicide studies based on samples of the general population within the United States are sorely needed to develop strategies for prevention. Several studies of maternal filicide separated results on the basis of proposed typologies of motivations among mothers who commit filicide. In some studies, the age of the child that was killed was reported, but there was no discussion of the child’s age in relation to the common factors in the lives of their mothers. The inclusion criteria for the age of the child victims varied drastically across studies, making the development of conclusions difficult. Because of the differing legal definition of infanticide among countries, comparison to U.S. incidence rates of filicide may be difficult. Based on our understanding of childhood abuse, we hypothesize that after the first day of life, risk factors for filicide are related to the age of the child. The literature supports the supposition that fatal abuse may be more likely to occur in younger children and that older children are more at risk from purposeful homicides. However, the existing research on filicide cannot be used to affirm this supposition.

The nature of filicide varies within the population of women studied. Consideration must be given to the appropriateness of the questions asked about the population and the selection of comparison groups. For example, within a mentally ill population, data should be sought to help inform clinicians why one mother with psychotic depression is more likely to kill her child than another mother with psychotic depression.

What we know about maternal filicide is specific to the population studied. Few factors are consistent across populations; thus overall, we know very little about which children are at risk for death at the hands of their mothers. All of the studies reviewed here were retrospective, and most were descriptive. None of the studies included calculation of relative risks for filicide in women with specific disorders or maternal characteristics strongly associated with filicide. However, they did provide general descriptions of mothers who had committed filicide, and from these descriptions we can extrapolate some potential risk factors. Women at risk for neonaticide are often young and unmarried, deny or conceal the pregnancy, and lack prenatal care. The factors associated with maternal filicide appear to be nonspecific but seem likely to include past use of psychiatric services and a history of suicidality and depression or psychosis. However, the factors associated with maternal filicide are likely to be different for women who are psychiatrically ill, compared to those who are not psychiatrically ill.

Investigators who conducted research in psychiatric populations often had access to detailed psychological information about the maternal perpetrators of filicide, but their conclusions are limited in generalizability. Maternal mental illness appears to play a varying role in filicide. Descriptions of filicidal mothers were highly dependent on the source of the sample. Imprisoned U.S. perpetrators of maternal filicide were understandably less likely to be mentally ill than mothers who were psychiatrically hospitalized. These differences in study populations make it difficult to draw general conclusions about which mothers are at risk. Furthermore, although there were few studies, some were difficult to categorize because they were based on very specific populations that may have had some overlap. For example, a study of women referred for psychiatric evaluation after commission of neonaticide (49) was classified as a psychiatric population study because it would have included a preselected group of women who were more likely to have psychiatric disorders than would a general correctional population, although it could be argued that such a population should be considered a correctional population because the women were pretrial detainees at the time.

This critical analysis suggests that clearer parameters are needed for research in this area. There is a lack of standardization in filicide research regarding the age of children who constitute filicide victims. The children in the studies we reviewed ranged from neonates to young adults as old as age 29 years. We propose that future filicide research consider including only children under age 18 years, because they are minors and still of school age. The existing studies did not examine the possibility that contextual factors may vary according to the age of the child victim. No study reported on characteristics of the mothers based on the age of the child who was killed, other than in cases of neonaticide or infanticide. It is interesting to note that when study population samples were separated by country, different factors appeared to emerge. Less variability occurred in the findings of neonaticide studies among nations than among population sample types.

Very few American general population studies were conducted. The epidemiological studies that do exist do not differentiate maternal filicide from other child homicides (69, 93). American infants at risk of homicide are known to be born to young, undereducated mothers with low socioeconomic status who do not obtain timely prenatal care. However, this research is limited by lack of classification of the homicide perpetrator as the mother, the father, or a nonparent. Psychiatric diagnoses are frequently made after the homicide, when women may develop depression or posttraumatic stress disorder in reaction to commission of the filicide. These diagnoses may not necessarily reflect the women’s psychiatric status before the filicide. Furthermore, it is often unclear how rigorously the psychiatric diagnostic criteria were applied.

In a closely related area of research, two studies found a high incidence of filicidal thoughts in mentally ill women (102, 103). The study by Chandra et al. (103) of postpartum severely mentally ill women in India found that 43% had infanticidal ideation and 36% exhibited infanticidal behavior. Infanticidal behavior was associated with female gender of the infant, adverse maternal reaction to separation from the infant, and psychotic ideas relating to the infant. These findings are a step toward developing a profile of mentally ill mothers who may be at risk for filicidal deeds. Further descriptive research is needed to explore the character and quality of parenting by mentally ill women (104). This area of research is important because approximately one-quarter of the women referred to psychiatric services have a child under age 5 years (104). Similar studies of women who are not mentally ill—particularly women who are young, poor, and undereducated and who fail to obtain prenatal care—are also critical. For example, a study in a nonpsychiatric population found that 70% of mothers of colicky infants had explicit aggressive thoughts toward their infants, and 26% of these mothers had infanticidal thoughts during the infant’s episodes of colic (105). Development of intervention strategies depends on a better understanding of the prevalence of these thoughts and the characteristics of mothers who are likely to act on these thoughts.

Received Aug. 29, 2004; revision received Jan. 7, 2005; accepted Feb. 23, 2005. From the Department of Psychiatry, Case Western Reserve University and University Hospitals of Cleveland. Address correspondence and reprint requests to Dr. Friedman, Department of Psychiatry/Hanna Pavilion, University Hospitals of Cleveland/Case Western Reserve University, 11100 Euclid Ave., Cleveland, OH 44106; [email protected] (e-mail). The authors thank Dr. Penelope Friedman and Dr. Jill Korbin for their insights. No financial support was given for this review.