Demand

The licence for unmediated obstetrics comes up for renewal every five years, and every five years the examiner asks me why I keep it. There are perhaps thirty thousand unamended people left in Britain, most of them out in the fen communities, and they have their own midwives, who are good, and who send me two or three referrals a year. Somebody has to hold the old medicine, I tell the examiner, and I am not yet forty and can hold it another thirty years.

The truthful answer is that the old medicine is the most interesting thing I know.

Twenty-six weeks. Tamsin Reeve came up from Welney on a Tuesday, with her notes on paper because that is how the communities keep them, and a glucose tolerance test that had come back at numbers I had only ever seen in textbooks. Thirty-one, first pregnancy, married to a man from another unamended family, which is the only way an unamended child gets conceived any more. She had driven herself. She sat down and said, “Alys says my sugar’s up, and that it’s the baby doing it. Which I took for her idea of a joke. Only she wouldn’t laugh.”

“It isn’t a joke,” I said. “Your placenta — which is your daughter’s organ, not yours; her cells, her genome — is secreting a hormone into your blood. By term it will be making grams of it a day. No gland in your body spends like that, not the thyroid, not the pituitary, nothing. And the one clear thing the hormone does is make your own insulin work badly.”

“Why would she want my insulin working badly?”

“Because everything your insulin locks away into your muscles and your fat is sugar that never reaches her. Blunt the insulin and the sugar stays in the blood, and the blood goes through her. Your pancreas answers by making more — most women double their output and hold the line. You’re not quite holding it. That’s all gestational diabetes ever was. You’re being outbid.”

She looked at her hands for a bit. “So she’s skimming me.”

“Yes.”

“And the hormone’s the crowbar.”

“One of them,” I said, and wrote her up for insulin.

What I did not try to explain in one appointment was why. Half the child’s genome is Tamsin’s, and a gene that came through Tamsin does well by restraint: the mother it is taxing carries copies of that gene herself, and will carry its siblings in later children, if she is left in any state to have them. A gene that came through Dan holds no such stake — it has no guarantee of ever seeing the inside of Tamsin again. Over the deep table of the generations, father-side genes prospered in children who took more, and mother-side genes in children who left something for the next. And because what profits them differs, they learnt to speak differently: a few hundred loci in the genome where a copy remembers which parent it came through and pitches its voice accordingly — the father’s copy loud, the mother’s silenced, or the reverse, depending on whose interest the gene serves. Imprinting, the old literature calls it, as though it were a stamp on luggage. It is closer to a treaty line.

You can read the division of labour straight off the old failures. An embryo that gets two paternal genomes and no maternal one builds almost nothing but placenta — a proliferating bag of invasion with nobody inside. Two maternal genomes and no paternal one: tissues, hair, sometimes teeth, and next to no placenta at all. The father’s half throws its whole weight at the supply lines; the mother’s half budgets. When researchers first made a mouse with two mothers, a century and a half ago, they managed it only by rewriting the genome at two loci so that a mother’s chromosome would pass for a father’s.

Thirty weeks. I was twenty-four weeks myself by then, and the comparison was unavoidable, and it ran all one way. I took my own readings at the clinic out of habit rather than need. Glucose flat. Pressure flat. The graphs of a healthy woman who happens to be pregnant.

The Concord edit is four generations old now, and people get it wrong in a particular way: they say it disarmed the children. It did not disarm the children; it disarmed the loci. Wherever the two copies of a gene had been set against each other — one shouting, one gagged — the Concord set both to speak once, quietly, at a dose worked back from first principles. The design notes are public, and they are some of the most careful engineering ever done: a matched de-escalation, every reduction on one side paired with its counterpart on the other, because the failures had taught them what one-sided disarmament builds. It went into the germline, it bred true, and within two generations of its licensing the whole apparatus of my profession’s old heroics — the magnesium infusions, the 3 a.m. sections, the sugar diaries — had contracted into a single licensing exam module titled historical presentations.

In Tamsin’s blood panels you could see what the module was about. Hormone poured against hormone, gram against counter-gram, and the net of it, once her insulin dose was right, close to zero. A visitor from some other line of evolution would ask why so much was being spent to move nothing at all. It is the physiology of a front that has not shifted in a million years. The old texts had a fact I kept returning to: there are women born without the gene for that placental hormone at all — deletions, a handful of families — and their pregnancies go fine. Grams a day, of something the pregnancy can do without. Nothing in biology spends like that except an argument.

Thirty-four weeks. Her pressure came up. Not far — one-forties, a trace of protein — but I moved her appointments to weekly, and she noticed what that meant, because she was nobody’s fool.

“Is she trying to hurt me?”

“Deliberately is the wrong word,” I said. “There’s no one there yet to deliberate. But accident is the wrong word too.”

I told her the part I had been keeping for when it was needed. That in her first trimester, cells from the placenta had gone into the walls of her uterine arteries and stripped the muscle out of them; that the vessels feeding her daughter could no longer be narrowed — not by cold, not by shock, not by Tamsin. That if she haemorrhaged tomorrow, her body would shut the blood to her own gut and her own hands before it could claw back one drop from the child. The tap was out of her hands by week twelve. And that the old disease we were watching for was the escalation that followed when a placenta laid down too shallow found the flow too mean, and poured signals into the mother that stiffened her whole circulation, forcing the perfusion up and up until her kidneys, her liver, her brain began to fail. The only cure anyone ever found was delivery. Which tells you what the argument was about.

“You make her sound like the bailiffs,” Tamsin said.

“Mostly it balances. It balanced for ten thousand generations. Everyone sitting on this side of the desk is the child of a war that ended level.”

“And your lot” — she nodded at me; I was visibly pregnant by then — “just called the whole thing off.”

“Both sides at once,” I said. “That was the trick nobody managed before. Evolution can’t sign anything. It can only escalate or lose.”

Forty-one weeks. She went into labour on her own, four days past the date, and pushed out a daughter of 4.3 kilograms — the shoulders took two manoeuvres and ten seconds I did not enjoy — who came up furious, fists going, a cry with an edge on it, rooting before she was weighed. “Ninety minutes old,” Tamsin said, from somewhere near the ceiling of her own exhaustion, “and already on at me.”

Afterwards I did what the old texts say and examined the placenta on a steel tray: seven hundred grams, the vessels at the bed gaping wide where they had been remodelled, the whole campaign’s quartermaster grey and done, an embassy shut in an afternoon. The unamended keep their placentas; there is a tree custom. I bagged it and signed it out to Dan like evidence.

After. At the six-week check Tamsin had the hollowed look I know from the old photographs rather than from my own patients. Feeding every ninety minutes through the night, she said. Alys had told her the fen truth, which is that it passes, and I told her the other truth, which is that the old literature read the waking as one more move in the same game: a child at the breast through the night keeps its mother’s ovulation suppressed, and every month without a sibling conceived was a month of undivided milk. The infants born with the father’s page missing at one particular locus slept beautifully, fed weakly, had to be woken to be fed at all. It is in the old case notes as a symptom.

“Yours sleep through, I hear,” she said.

“Mostly.”

“Lucky you.”

People ask — the unamended ask especially — whether we lost something. The cohort studies are clean, and I believe them, having run two: Concord children are not placid, whatever they say in Welney; they are as various as weather. The one thing the Concord measurably narrowed is birthweight. Bea was 3.4 kilograms, born at term plus one after four unremarkable hours, and she tracks the fiftieth centile like a train on a rail, and she has slept through since the eighth week.

I wake at three most nights anyway. I stand over the cot in the dark. Her breathing is even; her hands are open. Nothing is wrong. I check anyway.