Could you too be a killer mummy?

Women like Andrea Yates, who drowned her children, get off more lightly than murderous dads. But Ame

On the morning of Wednesday 20 June, between 9am and 10.30am, Andrea Yates drowned her five children in the family bathtub. The first to die was her youngest son, two- year-old Luke. Next came Paul, aged three. Then John, aged five. Then six-month-old Mary, Yates's only daughter. Seven-year-old Noah - who tried to escape - was then caught by his mother and drowned in the bath alongside the body of his dead sister. The killings completed, Yates phoned her husband, Russell. "You better come home," she said, then she called the Houston police and told them that she had killed her children.

Mothers spend much time bemoaning parenthood: the exhaustion, the frustration, the feelings of what we casually term despair. Few of us act upon these feelings, yet in one four-month period in 1998 alone, more than 50 American children were killed by the women who gave birth to them. In the ten days following the murder of the Yates children, there were two further maternal drownings, the latest in a long, tragic line.

Why should mothers kill? Through gross neglect, vicious rage, substance abuse, crazed ambition, or severe mental illness. Allison Harper punched her three-year-old son so hard that she ruptured his intestine. He died five days later. Post-natally depressed, Sheryl Lynn Massip placed her six-week-old son on the road and drove her car over him. Khoua Her strangled all six of her children. Susan Smith strapped her two sons into their child-seats and pushed her Mazda into a lake.

If, as the feminist anthropologist Sara Blaffer Hardy argues, "maternal instinct" is less a question of biological determinism than a conscious decision - no surprise to adoptive parents - how much harder is it if the mother in question is poor, ill-educated, under-age, sick, abused or addicted? It follows, then, that the vast majority of America's child homicides are "white-trash" infanticides. Or so we think.

Yates was neither poor nor ill-educated. A trained nurse and a graduate of the University of Houston, she had waited until her late-twenties to have her first child. She had a stable and apparently happy marriage to Russell Yates - a computer specialist at Nasa - and the loving support of an extended family. Her home-schooled children were healthy, bright and inquisitive. Noah loved butterflies. John loved ladybirds. Luke was perpetually smiling the same wide, eager smile of his parents. How many people must have seen Andrea walk them to the park or the bookshop, or play basketball with them and thought, "How does she do it?"

Seemingly, she did it very well. Until three months after Luke's birth in 1999, when post-partum depression (PPD) kicked in and Andrea attempted suicide - twice, according to her brother. She was prescribed a cocktail of anti-psychotic and anti-depressive drugs, including Haldol, commonly used to treat schizophrenia, and Wellbutrin.

When PPD struck again, after the birth of her daughter, she switched to Effexor and Remeron in a desperate attempt to recover. Whether she was offered progesterone treatment is not known, but the anti-depressants didn't work. Neither had the four separate periods of hospitalisation since 1999. As Yates told the police, she believed that her mothering had "disabled" her children. She felt she was "a bad mother". Had she said that to her intimates before the killings, they would doubtless have denied it. Now, at last, she will be believed.

American male commentators have recoiled in horror. Female commentators have rushed to empathise, recalling their own (presumably far milder) experiences of depression. But if we know what PPD is, and whom it can affect (four out of five mothers in its mildest form, one in 500 to the point of hallucinations and delusions, and one in 125,000 to the point of full-blown psychosis), do we need to touch it in order to believe? Post-partum depression respects no divisions of class, religion, age, beauty, or moral rectitude, but still the illness itself is on trial, with the airbrushed queens of prime-time as character witnesses.

Worldwide, the sentences for maternal child-murders are low, far lower than those meted out for spousal murder. In England and Wales, the maximum charge for infanticide is manslaughter. Why is this? The answer lies in our unconscious assumptions about the ownership of a child's life - the same assumptions that stoke the belief that a child is an extension of its mother. In secular societies, the child belongs to its parents. In religious societies, the child belongs to God. In the deeply religious state of Texas, where God wears Old Testament garb under his stetson, the rule is an eye for an eye. Andrea Yates is therefore facing five charges of capital murder - punishable by death.

In Houston, there is little liberal sympathy for a woman seen as having so many blessings. To many, Yates has destroyed the precious illusion that such murders are the province of poverty or evil.

For all the community projects that have sprung up across Texas to encourage responsible parenting among the poor, one educated woman with health insurance, a husband and a nice home still fell through the system and into madness. As far as we know, there is no abusive uncle in her background, no trashy sex life. That she had been obsessed by the idea of drowning her children for months - a common characteristic of severe PPD - has thus been popularly interpreted as intent to kill. The words used by the Harris County Police Department to describe the killings were "systematic" and "methodical".

Mothering is a methodical and systematic business. For the last seven years, Yates had methodically and systematically clothed, fed, nursed, changed and taught those children.

KPRC, Houston's TV station, opened a website discussion forum within hours of the news of the killings. "If Yates had post-partum depression should her penalty be lessened?" it asked. Within four days, the site had run to 37 pages. Among the hundreds of messages left, the calls for Yates's execution by lethal injection outnumbered those against it by approximately 15 to 1. In sex- and war-torn America, mothers who kill are seen as "getting away with it". Few paternal multiple filicides even reach trial as, in the majority of cases, the father goes on to kill himself. Natural justice, say some, but - crucially - the men who survive get far harsher sentences. Against this background of discontent, to defend Yates by way of temporary insanity will be doubly difficult. Should there be any hint of abusing the insanity plea in her defence - as has been hinted at in previous cases - it will be the last time the PPD defence is used in the US for a very long time. America is tired of the "hormonal" defence. It sounds too menstrual, irrational and self-indulgent. The feminists don't like it because it implies that women cannot think when they are bleeding or lactating. The "feminazi"-haters don't like it because it reminds them of their mothers. But hormones are chemical - as chemical as any psychotropic drug. For Yates, a post-partum hormonal imbalance was apparently intense enough to induce full-blown psychosis. Should this excuse the murder of the Yates children? No. Not for one moment. Should it mitigate their mother's sentence? Yes. A psychotically induced obsession with drowning is not the same thing as a cold-blooded plan. And if there is culpability here, it is on the part of doctors who failed to intervene after two suicide attempts and four hospitalisations. Andrea is now on suicide watch at Harris County Jail, delusional and barely capable of communicating. Over the next month, more will emerge about her: school yearbooks, past lovers, medical reports. Will they tell us when she last felt in ownership of her mind and body? We know that Russell Yates wanted "as many children as God wanted", but will we ever learn what Andrea wanted? If the woman who killed her children was, in her husband's words, "not herself", the woman standing trial will be a different person again. It's a bitter irony that, in preparation for her trial, Andrea Yates may finally receive the treatment she needs to restore her sanity. And then she will indeed suffer unbearably.