Obstetric Pharmacology

Inducing and Augmenting Labour: Oxytocin and Prostaglandins

A pregnancy has run past its date, or a membrane has ruptured with no contractions to follow, or a labour has stalled halfway. In each case the obstetrician must persuade a reluctant uterus to do what it will not do on its own — and there are only two levers to pull. Soften and open the cervix so it will yield, and drive the muscle of the uterine body to contract in a rhythm strong enough to deliver. Two drug families own those two jobs: prostaglandins ripen the cervix, and oxytocin powers the contractions. Learn how each works, and — far more importantly — where each turns dangerous, because the same drugs that start a labour can, pushed too hard, choke the baby of oxygen or poison the mother with water.

Tocolytics and Preterm Labour: Buying Time for the Baby

A woman arrives at 29 weeks, contracting, terrified her baby is coming far too soon. There is a drug that will quiet her uterus — but here is the twist that trips up every student: it will not, by itself, make her baby do any better. Tocolytics don't cure prematurity. They do one modest, priceless thing: they buy roughly forty-eight hours. And in those forty-eight hours you give the two interventions that genuinely change the baby's future — a course of steroids to ripen its lungs, and time to move mother and baby to a unit that can care for a tiny newborn. The tocolytic is the bridge, never the destination.

Postpartum Haemorrhage: The Uterotonic Ladder

A woman can lose her entire circulating volume through her uterus in minutes. Postpartum haemorrhage is one of the leading causes of maternal death worldwide, and yet the pharmacology that stops it is strikingly simple in principle: a delivered uterus should clamp shut around the raw placental bed like a fist, and when it fails to, you make it contract. That single idea — make the uterus contract — organizes an entire emergency: a ladder of uterotonic drugs climbed one rung at a time while blood is replaced and clot breakdown is halted. Knowing the order of that ladder, and the two contraindications that can turn a rescue drug into a catastrophe, is the whole exam and the whole bedside.

Hypertension and Pre-eclampsia in Pregnancy: Safe Drugs and Magnesium

Pregnancy rewrites the pharmacology rulebook. A blood-pressure drug that is first-line for everyone else can maim a fetus; a salt that no one thinks of as an anticonvulsant becomes the single most important drug on the labour ward. Hypertensive disorders of pregnancy are less about pushing a number down than about choosing agents that will not harm the baby — and knowing that when the mother is on the edge of a seizure, the answer is not a benzodiazepine but magnesium. Get the safe list, the teratogen list, and magnesium toxicity right, and you have the whole chapter.