For years, it has been the belief of the scientific community that gestational hypertension and pre-eclampsia were relatively unique to humans, although there has been some recent evidence that other primates can also develop similar conditions, albeit due to different underlying mechanisms. The underlying cause of gestational hypertension in humans is commonly believed to be an improperly implanted placenta. Humans have evolved to have a very invasive placenta to facilitate better oxygen transfer from the mother to the fetus, to support the growth of its large brain. Origins of the placenta
The origins of gestational hypertension may lie with the development of humans hemochorial placenta. A hemochorial placenta optimizes the amount of oxygen and nutrients that can be absorbed into the fetal blood supply, while at the same time ensuring rapid diffusion of wastes away from the fetus. This hemochorial placenta differs from lower primates epitheliochorial placentae in the way that it allows the fetal tissues to interact directly with the mothers blood. The hemochorial placenta thereby promotes more rapid diffusion to and from the fetal blood supply.In animals with epitheliochorial placentae such as horses and pigs, the greatest resistance to maternal blood flow in the vascular system was found within the placenta. However, in animals with hemochorial placental structures such as rodents and primates, the vascular resistance in the placenta was low, leading scientists to the conclusion that the greatest resistance to maternal blood flow is found elsewhere in the maternal vascular system.
It is a combination of three medical conditions: hemolytic anemia, elevated liver enzymes and low platelet count. Eclampsia
This is when tonic-clonic seizures appear in a pregnant woman with high blood pressure and proteinuria.Pre-eclampsia and eclampsia are sometimes treated as components of a common syndrome. Treatment
There is no specific treatment, but is monitored closely to rapidly identify pre-eclampsia and its life-threatening complications (HELLP syndrome and eclampsia).Drug treatment options are limited, as many antihypertensives may negatively affect the fetus. Methyldopa, hydralazine, and labetalol are most commonly used for severe pregnancy hypertension.The fetus is at increased risk for a variety of life-threatening conditions, including pulmonary hypoplasia (immature lungs). If the dangerous complications appear after the fetus has reached a point of viability, even though still immature, then an early delivery may be warranted to save the lives of both mother and baby. An appropriate plan for labor and delivery includes selection of a hospital with provisions for advanced life support of newborn babies. Evolutionary considerations
Humans
Gestational hypertension is one of the most common disorders seen in human pregnancies. Though relatively benign on its own, in roughly half of the cases of gestational hypertension the disorder progresses into pre-eclampsia, a dangerous condition that can prove fatal to expectant mothers. However, gestational hypertension is a condition that is fairly rare to see in other animals.