Pre-Eclampsia: Is It All In The Placenta?

Hypertensive disorders of pregnancy complicate almost 7 – 10 % of all pregnancies. The dyadof hypertension and proteinuria after 20 weeks of gestation is referred to as pre-eclampsia. It is amajor cause of maternal morbidity and mortality and is also associated with increased perinatalproblems. Despite intensive research over the years the exact cause of pre-eclampsia remainsunknown. Nevertheless, information gleaned from published studies point to the placenta as theprobable pathogenetic focus of pre-eclampsia, as the disease usually resolves within 24 – 48 hoursafter delivery of the placenta. Although the precise involvement of the placenta in pre-eclampsiaremains unclear there are indications that the trophoblastic invasion of the uterine spiral arteries isabnormal in women who develop pre-eclampsia. This impaired invasion leads to decreased placentalperfusion and ultimately to placental hypoxia. The distressed or ischaemic placenta then secretesa factor(s) into the maternal circulation, which cause/s widespread endothelial cell dysfunctioncharacterized by vasospasm, activation of coagulation system and organ ischaemia. The cause of thedefective cytotrophoblastic invasion of the spiral arteries and the link between placental ischaemiaand generalized maternal endothelial dysfunction remain unknown. Although the placenta appears tohave a major role in the pathogenesis of pre-eclampsia, evidence also suggests that factors like maternal genetic predisposition, dietary, environmental and behaviour, which surface during the stress of pregnancy might also be involved in the development of pre-eclampsia. It is known that not all women with poor cytotrophoblast invasion develop pre-eclampsia and not all women with preeclampsia show poor cytotrophoblast invasion. Over the years, a number of potential risk factors associated with the development of pre-eclampsia are being recognized and it might be appropriate now to develop some preventative strategies based upon the available information