Classification of pre-eclampsia into early and late pre-eclampsia

The terms early versus late pregnancy is becoming widely accepted as a better indicator of disease significance than the classic terms "mild" or "severe" pre-eclamsia (1).

There is evidence that early onset (before 34 weeks of gestation) is associated with severe pre-eclamsia.

• early onset pre-eclamsia is thought to be due to involvement of the placenta with associated
  • abnormal uterine artery Doppler flow
  • fetal growth restriction
  • adverse maternal and fetal outcomes
• late onset pre-eclampsia (after 34 weeks of gestation) appears to be due to maternal "constitutional" factors, such as body mass index (BMI) and is considered to be associated with a more favorable outcome

Other than the aetiology of the disease, maternal haemodynamics appear to vary according to the time of presentation. A study conducted with 1345 nulliparous patients identified as normotensive with bilateral uterine notching at 20-22 weeks' gestation found out that

• women with early disease had higher total vascular resistance and lower cardiac output
• while late onset women had higher pre-pregnancy BMI, higher cardiac output, and lower total vascular resistance when compared with the early onset and control patients (1)

Reference:

• 1. Turner JA. Diagnosis and management of pre-eclampsia: an update. Int J Womens Health. 2010;2:327-37