Eclampsia needs a placenta, and ends when the placenta is gone
Eclampsia, the seizures that can strike pregnant women with pre-eclampsia, has a puzzling requirement: a placenta. Remove the placenta and the condition resolves. Its forerunner, pre-eclampsia, even appears in molar pregnancies, where there is no fetus at all. Exactly why remains poorly understood, though reduced blood flow to the placenta seems central.
Pre-eclampsia is a blood pressure disorder of pregnancy marked by newly raised blood pressure, heavy protein in the urine or other organ trouble, and swelling. It is diagnosed after 20 weeks of gestation and usually appears in the third trimester. Eclampsia is the step beyond, when seizures arrive; most occur before delivery, but they can come during labour or afterwards, most often within 48 hours of birth, and anywhere up to 6 weeks postpartum.
Warning signs often precede the first seizure by hours: persistent headaches, blurred or double vision, discomfort in bright light, and pain high in the abdomen, though some women have no symptoms beforehand. The seizure itself is tonic–clonic, beginning with stiffening that lasts about a minute before jerking movements, and followed by confusion or coma. It usually leaves no lasting brain damage unless there is bleeding inside the skull.
Globally, pre-eclampsia affects about 5 per cent of deliveries and eclampsia about 1.4 per cent. With better care, rates in the developed world are around 1 in 2,000 deliveries, while developing countries can see 10 to 30 times as many cases. Hypertensive disorders rank among the most common causes of death in pregnancy. Risk is higher in first pregnancies and among women with earlier high blood pressure, diabetes or kidney disease.
For the fetus, eclampsia can slow growth in the womb and cause bleeding problems in the placenta. In the mother, resistance in the brain's blood vessels drops, flooding it with blood and causing swelling that triggers convulsions. Magnesium sulfate, given into a vein or muscle, improves outcomes, and low-dose aspirin is recommended for women at high risk to help prevent the condition. Researchers are also testing first-trimester blood markers that might flag pre-eclampsia early.
Source: Eclampsia
