It can occur without warning at any time during pregnancy, with some women developing early-onset pre-eclampsia before 34 weeks, and others experiencing late-onset forms of the condition.
Women can even suffer from postpartum pre-eclampsia in the six weeks after giving birth.
Excessive inflammation, beginning in the uterus, disrupts the delicate communication patterns taking place between the mother's body and the foetus.
In particular, it impacts the reshaping of blood vessels within the uterus to form the placenta, the organ created to provide the foetus with the nutrients and oxygen it needs.
Because the flow of blood through the placenta is abnormal, it ultimately interferes with how the mother's body controls blood pressure, gradually leading to hypertension and ultimately pre-eclampsia.