I read Lauren Slater's book last month, when I was pregnant. As I write about it, now, there is a baby in the room; or more openly in the room. The difference between "then" and "now" is more than one of degree. The world has changed. As for myself - well, now I can type. Then, I could do nothing but read a little and, in the occasional clarity that comes at the end of pregnancy, admire the light from the landing as it came in around the bedroom door - all this as I timed more useless contractions, and the future got so near I could almost touch it. Pregnancy would be a very intense experience if you had the energy; if, indeed, you had any kind of definite "self" to experience the intensity. The edges get fuzzy. Last month, I had problems with words and numbers, as anyone might when tired, but I also had problems with three-dimensional space: I experienced a kind of flattening; very expressionistic; very like an effect I used to get way out on the edge of depression when the world went a little "off". The only difference between late pregnancy and depression that I can think of is that loss of a sense of self - at nine months, you feel like a vegetable; when depressed, you feel like a very important vegetable, or a hugely worthless one.
No one tells you what happens to your brain. I read somewhere that pregnant women lose 3 per cent of their brain volume. I asked my obstetrician about this; she laughed and said, "You'll never get it back." Ho ho ho.
"It is difficult to move, my limbs say no. I stand at the top of the stairs, holding on with one hand to the newel post, looking down the slant, and considering." In the first trimester of her pregnancy, Lauren Slater got some answers as to what was happening to her brain and none of them was very encouraging. She was filled with admiration for the 94 per cent of the world's women who, by getting pregnant, "agree, knowingly or not" (whatever that might mean), "to navigate the most difficult terrain of the brain". Slater's sentences are more in thrall to rhythm than to sense, though under their precise, seeming lucidity there is important information about what pregnancy is actually like. Or perhaps it is madness she is describing. Slater herself is not in a position to tell.
Psychomotor retardation, disturbed sleep, disturbed appetite and "neurovegetative symptoms" are symptoms that are common to both depression and pregnancy. This sameness is of great interest to Slater; after ten years on Prozac, she has decided to give up her medication for the sake of the foetus, and the question whether she is going mad or if this is just "week 15" is an urgent one. Sadly, as her behaviour becomes more florid, she is obliged not only to go back on Prozac, but to top it up with lithium and Klonopin, and you cannot help but feel for her, and for her baby, as she makes the decision to be sane.
"Can a mentally ill woman be a good mother?" she asks. Slater lives in the difficult space between biology and psychology, so we do not know if she is asking whether, as a mentally ill woman, she could make a good breeder, or a good mother to the child once it is out. You might answer that the mothering is more within her control, and the breeding is her own business: this, however, would be a very European response; her American sisters on the internet are frequently horrified by who is allowed to reproduce these days, up to and including women who drink too much Diet Coke.
Once on her Prozac cocktail, the rest of the pregnancy goes quite well: in fact she is so blithe, I ended up feeling almost jealous of Lauren Slater. She swims for 40 minutes a day. She despises the other women in her antenatal class for looking fat. Her mental illness is an edgy, overachieving sort of thing; there is very little slobbing about in a dressing gown or crying at adverts for toilet tissue. There is also, strangely, very little interest in her morphing body, or the new life inside it. Although she says that "the child is yours because you have imagined it", Slater does not suffer from the pregnant woman's sense of wonder. This might be a side effect of the drugs, or it might be a function of that very precise prose style. Slater is too intelligent to fall into the traps, to which American women are prone, of being very aggrieved or very empowered by pregnancy. In this book about feelings, she admits to not knowing how she feels, and this is admirable. For her, as for many people who live a medicated life, the bottom line is chemical, and here it is: Slater's perinatal psychologist tells her that there is such a thing as antenatal depression, a fact so little advertised that she, a psychologist herself, had never heard of it. This depression hits in the first trimester of pregnancy, when progesterone levels are high, and it predisposes the mother to the ravages of post-natal depression. Women who suffer from pre-menstrual tension, who have a depressive reaction to the Pill, or who showed signs of a mood disorder at the onset of puberty are particularly vulnerable. As Slater writes: "Ten to 15 per cent of all pregnant women experience what is called antenatal depression, oftentimes severe, sometimes psychotic."
Miserable mothers are everybody's business: nearly half of us become mothers and we all had one. Slater says that between 30 and 80 per cent of the mothers of pre-schoolers are depressed - a figure so vague, you'd be better off looking at faces in the supermarket. You do want her to get the statistics right, because this book contains information that every woman should know, and very few do. We rarely talk properly about pregnancy. The pregnant woman is a miracle, or a freak, or sometimes a nuisance; she is outside the normal run of things. She is an animal. She is underdescribed.
In the labour ward, I ask the midwife: has she ever delivered a psychotic woman?
"No," she says, looking thoughtful.
It is the middle of the night. Up and down the corridor the world is changing. We are surrounded by women blissfully numb from the waist down.
"How could you tell?" I say, and we laugh. In another hour or so, the baby will be born.
Anne Enright's most recent novel is The Pleasure of Eliza Lynch (Jonathan Cape)