The Lefebvre case is the 1925 killing of a pregnant daughter-in-law by her sixty-year-old mother-in-law, Mme Lefebvre. In Simone de Beauvoir’s account, it gives a horrifying outcome to an escalating conflict over maternity: the older woman, desperately attached to her own identity as a mother, treated the younger woman’s pregnancy as a threat and killed her. The case does not stand as an isolated eruption of inexplicable female violence; it is placed within an analysis of how women’s social situation and the meanings imposed on motherhood can shape intimate hostility.

Background and Family Conflict

Mme Lefebvre was a bourgeois woman from the North who lived with her husband and children. Simone de Beauvoir describes her as having long hated her daughter-in-law. The conflict sharpened when the younger woman was suspected of being pregnant: the announcement of pregnancy was the point at which, in the book’s account, Mme Lefebvre decided to kill her.

The episode follows an analysis of the tensions that may arise between a mother and her son’s wife. The mother can interpret the new relationship as an intrusion and watch the daughter-in-law for signs that confirm her distrust; pregnancy intensifies the conflict by making the younger woman’s place in the family and the continuation of life beyond the older mother newly visible. Mme Lefebvre’s actions exemplify the extreme end of that pattern, rather than establishing that such violence is typical.

The Killing and Its Circumstances

In August 1925, during a car trip, Mme Lefebvre killed her daughter-in-law, who was six months pregnant, while her son was driving. After suspecting the pregnancy, Mme Lefebvre had bought a revolver, supposedly to defend herself against robbers. The stated explanation masked the weapon’s connection to the family crisis that preceded the murder.

Mme Lefebvre was condemned to death and then pardoned. She spent the rest of her life in a reformatory and showed no remorse. She believed that God approved of the killing, which she compared to removing a weed, a bad seed, or a savage beast. The only act of defiance she offered as evidence against her daughter-in-law was the young woman’s statement that, since she was now part of the family, Mme Lefebvre had to take her into account. That ordinary assertion of recognition and standing became, in the older woman’s account, justification for murder.

Maternity and the Book’s Interpretation

The case is linked to Mme Lefebvre’s intense attachment to maternity after menopause. For twelve years she had suffered ailments that manifested themselves, in Simone de Beauvoir’s description, as an imaginary pregnancy. This detail makes the murder part of a longer crisis of identity: the daughter-in-law’s actual pregnancy arrived in a life where Mme Lefebvre remained bound to motherhood even after her own reproductive period had ended.

In the surrounding argument, motherhood is neither a simple biological destiny nor an uncomplicated source of fulfillment. The book describes reproduction as a bodily reality that can impose hardship, while insisting that biological facts acquire their meaning within social and psychological circumstances. It likewise argues that the body is essential to a woman’s situation but cannot alone define her or explain her subordination. Read in this framework, the Lefebvre case shows maternity turned into an absolute claim: Mme Lefebvre’s imagined and possessive attachment to being a mother culminates in the violent rejection of another woman’s pregnancy.

Significance

Simone de Beauvoir uses the case to make the stakes of intergenerational conflict concrete. The daughter-in-law’s pregnancy signifies a future that does not belong to the older woman; Mme Lefebvre experiences that change not as continuity but as displacement. Her belief that the killing had divine approval and her lack of remorse reveal how thoroughly she rationalized the act, while the contrast between that justification and the young woman’s modest demand to be taken into account exposes the gulf between domination and reciprocal recognition.

The case is a specific, extreme instance, not proof that biology dictates violence or that maternal attachment inevitably produces hostility. Its force lies in the opposite claim: bodily and reproductive conditions matter, but their consequences are shaped by history, social relations, and the meanings people attach to them. The victim was six months pregnant; the perpetrator had spent years imagining pregnancy after menopause; and the murder turned their unequal, competing claims around maternity into an irreversible act.